Did you ever give up an animal despite decent conditions?

I currently have two black cats about 5 years in age. I got them as kittens from a friend because I didn’t want them to go to a shelter. My former partner grew up with cats so they would sleep with us and cuddle with us, etc.

Fast forward a year or so we split, helped someone crash at my place and they brought their cat. From there on things were never the same. My cats went from being super bonded to very defensive, not aggressive at all towards people even babies. Then I don’t know where in all the chaos one of my cats turned out pretty chunky and I’ve never been able to bring her weight down. One cat likes to nibble and the other will swallow food wherever presented. I bought a cat feeder with a sensor to portion out her meals but I don’t know if I did it right. They’ve gotten a little better but whenever the chunkier cat is “hungry” she meows continuously and gets really tense with the other cat.

On top of that my fiance is allergic to them, he tried to allow them on the bed but we realized no matter what part they slept at, he would break out in allergies so I decided to keep them off the bed.

I recently put my almost 2 year old in daycare because my work has starting picking up and I was just realizing how much time my cats really need / how much I don’t give them because the chunkier one needs an actual diet plan /exercise plan. I had thought about just having one but i feel like they would just be bored and that’s no life either.

I just want them to have a good life, especially the chunkier one because I feel like her tiny little joints are going to suffer later because of if. I don’t treat them bad by no means but I just can’t give them life I want them to have.

My biggest thing is that I hate the idea of giving up cats when there’s so many in shelters looking for a decent home 🙃🙃 any cat owner/pet parent advice would be greatly welcomed