Can kitties grow apart?

Izzy(female) and Sebastian(male) have grown up together and for the most part (excluding Izzy's false heat bouts)had always loved each other. They are both indoor kitties & both fixed.
Recently I was married and when my husband & I returned from the honeymoon we found our kitties had gotten a divorce. Actually Izzy wants Sebastian out of her house. We've had Sebastian longer and he is the affectionate one that acts like he loves us while Izzy, if she demands it, will allow us to pet her on occassion.
It seems she wants to be in a one kitty household but we've always been a two kitty household and in fact we got Izzy when Sebastians best kitty friend passed on and he seemed lonely. It's been almost a month of Sebastian being the innocent, sweet, little victim and it's breaking our heart almost as much as the thought of giving Izzy up.
We've tried all of the herbal remedies and tried separating them, not separating them and allowing them to "work it out" on their own, bringing Sebastian to bed and locking Izzy out and vise versa.
Does it make us horrible kitty parents if we find Izzy a home where she can be the queen? Also, is it possible for kitties to grow apart as they grow up?

Has Izzy been to the vet to rule out illness? Kitties can hide illness well. There may be a problem.

There are also kitty meds to calm your cat if she has become viscous.

She may be reacting to your new hubby and the new dynamics that causes in the household. Sometimes change will bring on stress.

Did you have a cat sitter while away? There may have been a trama while you were gone.

Well, my husband & I were together (yes living together & yes we took our time) for 8 years before being married so I don't think it's that.
There have been no injuries & the kitties know the sitter well. The behavior has been occuring for approx. 1 month.
Medicinal remedies have been tried.
After going through the forums more completely I discovered similar problems all over the place with similar responces.
My real question is: Can kitties grow apart as they grow up?

In my experience, cat relationships go through phases. With my cats, they will change alliances from one year to the next. Sometimes there will be two who like to sleep together and are buddies for a year (or a few months) but then they will tire of each other and will either ignore or be quite irritable with the former buddy. Then several months (or even years) later, they become buddies again. So, as long as there is no real aggression (violent attacks) I wouldn't worry about it. In the meantime, whenever they are in the same room together and not being hissy or growly, make sure you praise and give them both lots of attention. That way they will associate the other with good things happening.

Again, unless there are violent attacks, just let them work through this phase. Continue giving them both lots of love and attention, especially when they are both being calm around the other.

Congratulations on the marriage!

Thank you for the responce (& the congrats).
I recently spoke with a next door neighbor that told me her own horror story about her two cats that started out loving each other and ended up hating each other. She claims it got worse over time and that's what really made us worry.
My husband & I are not about to give up our own little demon all that easily, but it would be a lie to say we weren't thinking of it. We want both kitties to have a happy, safe home and we're still hoping this will be just a phase.
Unfortunately I was watching the whole dynamic we have going on and it worries me. We sit downstairs with Sebastian showering him with love because we feel so guilty that he's no longer (because of Izzy) allowed to sleep under the covers with us. He spends the whole time latched on to us purring happily until we have to ditch him. If Izzy comes in the room we've always done exactly as you suggested ~ coo at how wonderful both kitties are and tell them how much we love them. She is always the aggressor. He will allow her to get closer and closer, even sniff his face, all the while with us gushing and she'll still attack him or, if the mood strikes her, she'll attack us.
I'm defining it as an attack because he's got scratches on him and he fears her unless he's sitting on our lap or very near us. We break up the fights because it's impossible to stand idly by. When we break up the frenzy there is little or no yelling we simply separate them, grab her and put her in her room with the door closed.
The dynamic I'm displeased about is that I don't like Izzy so often being confined any more then I like Sebastian always being the victim.

Is Sebastian sick? In my experience cats even after living together will not tolerate an unhealthy cat.

If both cats are healthy, then it's most likely a phase. I've just been through a phase where Russell and Esper could not tolerate each other except at meal times when a truce had to be called. This lasted for about 6 weeks. They like each other again and even share the scratching post once again.

Thank you for concern, Sebastian isn't sick...except maybe sick & tired-of being Izzy's personal scratching post!

Assuming that they are both healthy and Izzy is not in pain or something that would trigger this change, I wonder if there was some event outside the window while you were gone that would cause Izzy to displace her aggression onto Sebastian?

For instance, a tom cat might have been spending a lot of time outside your house and Izzy, being territorial as all cats are, wants to defend her turf. But since she's indoor she can't take it out on the outside cat and then takes it out on Sebastian (hence the name displaced aggression). Because you were gone, there was no one around to correct this and diffuse the situation and every day since she has felt the need to defend her turf (allbeit on the wrong kitty).

Have you tried completely separating them and then reintroducing them as if they were complete stangers to each other? There are a lot of threads here on how to do that. (rubbing each of them in their bedding so that they both smell the same etc.)

Before you begin the reintroduction have you gotten a Feliway Plug-in? If not, get one or two — I swear by these things. .. they have made our household much more peaceful.

Good luck!

Thank you for your input, Mr. Catzilla also found it very insightful. We've got the feliway already because Izzy's flipped on Sebastian before - cool to know it comes in "plug-in" form, didn't know that.
You're right on the money about the Tom cat, actually a cat named Tommy no less. He doesn't bother Sebastian but when he comes around Izzy, she flips her lid, needless to say our mini-blinds have never looked the same since.
I'm off to go read about the 'reintroduction' process so I can deal with my cats misdirected aggression...then it's off to cat owner therapy.
~Mr. & Mrs.Catzilla + Sebastian & Izzy

How cool it is that I found this site becuase I was wondering about this same subject just last week! Tybalt is four and male and Maddie is one and female. They took to each other right away when we brought Maddie home. They have always played and slept togther. I noticed a few weeks ago that Tybalt would hiss at Maddie whenever she came around, in his way, getting our attention,ect. This went on for a week or so. I didn't know what to think, was Tybalt sick or was he just tired of Maddie being the boss, (she is the typical female you know). My boyfriend assured me that it was just a phase and they would work it out so we just kept a close watch on his behavior. And, what do you know? They're back to loving each other again. We like to say that they just had a disagreement about who was to get the top perch on the kittie condo or something. Whatever it was it seems to be over. My point is that I agree that it is probably just a phase, and I would hate for you guys to have to ask Izzy to move. Although his aggression seems a lot worse than Tybalts I would still give it awhile. Keep me posted on the reintroducing. If Tybalt does it again I will have to keep that in mind. ....Good luck...

I would venture a guess that something happened while you were away that created this rift.

Have you tried making them smell the same by using vanilla extract under their chins and at the base of their tails?

Also I found that playing classical music very softly in the background calms the most agitated of cats down fairly quickly. Harp music works miracles!

You know, most of my cats end up disliking each other as they grow older. But I now have two cats, mother and son, who did just the opposite. They are as close as I have ever seen two adult cats. I thought it was normal for cats to grow apart as they grow older until these two cats came along. I think it is very sweet. But I worry about one of them grieving itself to death if something ever happens to the other one. They are extremely close to each other. Is that possible?