Ever since my cat has been going outside a lot...he's been using the litter box less and less

now i don't think he even uses it it at all...cause eh goes out a lot...my concern is today it's been raining so he's been in all day...I seen him a couple times walk up to the litter box, look at it and then walk away...I thinking he wants to use it...? idk...can a cat become so used to going outside that they don't use the litter box anymore....if he really needs to go...why doesn't he just use the litter box...or is him stopping and looking at the litter box just some random thing????

No, he is considering it. If he goes outside, he has become used to a clean spot every time he goes, and he doesn't like the litter box because he still has some odor in it from previous use. Try to keep it as clean as possible for him.

I have two cats now, and the first one I had doesn't like to use the litter box if the new cat has used it. He does the same thing as yours- walks over to it, even scratches around, sniffs, then walks out without using it.