Separating two cats and adopting a new one?

Hi everyone. I haven't been on this forum in a while! I guess that's a good thing since that ultimately means we haven't had any big problems with our cats. Well, there is a bit of an issue now, and I'd like your opinions. Sorry in advance for all of the details, they just seem very necessary for this.

My boyfriend and I have two cats - Momo and Beanie. They are both turning 3 years old this year. I adopted Momo when she was around 2 months old and we both adopted Beanie after we moved in together, when he was 6 months old.

Due to personal issues, my boyfriend and I are moving out to live on our owns for awhile, but stay together. (We are both young, I am turning 22, and he is turning 23. I've wanted the experience of living on my own.) Anyways, BF is moving back in with his parents to save money for a few months, where I have already moved into my new apartment. Since his moving in with his parents is temporary and his dad is allergic to cats, I've taken both for the time being.

Momo is a mama's girl. She loves me, and we understand each other. Honestly it baffles me how much we are to each other. There was no question that Momo would come with me. She is very intense, and before adopting Beanie she acted out. I don't believe she would ever do well as a single cat unless I was by her side 24/7, showering her with infinite amounts of affection. I would if I could, but that's not how it can be.

Beanie, on the other hand, is very... sensitive? He likes peace, quiet, food, and has his own little "getaway" places in the apartment. Since moving though he's become much more affectionate with me. He gets a long with Momo well enough - but BF and I think he would do okay being on his own. I don't think he would prefer being alone over being with another cat, but I could be wrong. BF wants to take Beanie with him.

The problem lies that I obviously don't want Beanie to go. He is such a sweetheart, and I feel he is "sensitive". He hates moving and adjusting, getting in his carrier, and I think Momo being there helped him, as much as Beanie being there helped Momo. I feel Momo is more dependent on Beanie though, and don't want to keep Beanie here if he would do better on his own.

So here is where I need advice... What do you think about separating the two? Here's the scenerio if they are separated: I've already decided that if BF takes Beanie, then I will get a second cat, because Momo is way too overbearing and would get so lonely when she didn't have Beanie. BF would not be getting a second cat, so Beanie would definitely be on his own. Momo needs another presence to not go absolutely insane - so how soon would be too-soon, in your opinions, to start looking and the "introducing a new cat" process, should that be the only option?

And if you think we should keep the two together - do you have any resources or life experiences I can share with my BF?

Or, if you have ideas on how to figure out what would be best, definitely share.

I would also like to note again that BF and I will still be seeing each other regularly. The moving out is just us needing space to grow and figure ourselves out. He will be visiting/staying with me every so-often and I with him.

Thank you for reading!

My immediate advice would be for you to keep Beanie since he and Momo get along, and BF can maintain his relationship with him as long as he keeps seeing you.  You already said BF's dad is allergic to cats so Beanie can't go there, and that will be for a few months.  See how Momo and Beanie do with you and try to observe if they are attached to each other.  You said Momo does better with a second cat, and it would certainly be less upsetting to her for you to just keep Beanie. 

When BF actually DOES move out of his parents' house, you can have this discussion in earnest.  At that time you will see if the two cats are bonded with each other -- i.e. they sleep together, wash each other, follow each other around, and act as a pair instead of two individuals.  If that is so, then BF should get himself another cat.  If the two of you ever move back in together, you can integrate the extra cat into your home.  If not, then BF has his own cat, and you have your two, without having to upset them. 

Thanks for your response. I feel like the cats are both accepting of each other but not so much on an "attachment level" both ways. Honestly it seems like Beanie isn't particularly attached to Momo, but Momo is to Beanie. Momo is always checking out Beanie, follows him, and will run up and start licking him suddenly. Beanie tolerates it all and allows it to happen, but normally, he doesn't initiate any of those activities. I feel like Beanie is a calming presence to Momo because he is generally chill when he's not frightened by a loud noise or anything unfamiliar, and he's predictable. I feel like he makes a good cat-friend to her. Beanie seems to be more of an "individual" but he's only ever been with other cats, so it's hard to tell if he would be lonely on his own or not (because BF would definitely only have one cat).

So it would obviously be better for Momo to just keep Beanie with me, but Beanie may or may not do better as a single cat. If Beanie did go to BF's new apartment in a few months, he would be alone most of the day and - I don't know. It makes me sad to think he would be alone if he's not used to it.

Just because the two of you adopted Beanie together doesn't mean that BF automatically gets custody if you split.  I think you should keep custody for the sake of the cats.  If something is working (i.e. they get along0, don't fix it (by breaking them up).