My fiance and I took in a stray female kitten about 3 months ago. She was 2 months old at the time, so 5 months now. She showed up at my fiance's coworker's door and once my partner saw the pictures, she wanted her.
I'm going to be honest and say that I didn't want to take her in. My fiance must have asked over 30 times in 2 weeks. She was in tears pleading before I finally caved. And I regret it. I regret it a lot.
We are not equipped to handle her. We live in a loft style apartment with only one door (to the bathroom). She doesn't have enough space to be a cat, and we're gone an average of 9-10 hours a day for work.
Our cat can be really sweet when she's calm, but that's increasingly rare as she gets more bored with the lack of human companionship. She's even losing interest in her toys and I just don't think this environment is good for her.
Beyond that, I just need space from her. My job is stressful (as is my partner's) and I don't have the mental or physical energy to give this kitten attention, and nowhere to go to get a break. It's reached a point where I dread coming home and I enjoy work more.
This cat is just an unrelenting ball of energy. She's destructive, she doesn't know what boundaries are, etc. And while none of that is her fault, I'm just not ready for it. I have too much on my plate already. I even started therapy just to try to find ways to cope, but I'm frequently the target of our cat's play aggression and none of the therapy exercises help me deal with that.
I am stuck doing most of the cat duties because, despite her repeated assurances, my fiance will not step up and do much to care for her.
But at the same time, I worry about what her life will be like if we send her to a shelter. Where should I even begin? The vet we got her fixed at just said "well, what did you expect? She's a kitten." Which is true, but not very helpful.
One of the things I found useful for occasionally setting boundaries is "time out", ie, shut her in your bathroom for about 5 min when she's really bouncing off the walls. I wouldn't use it as a more than once a day kind of thing, but sometimes communicating "this is too much, we are not playing right now and you can come out once you calm down a little" can reset the mood quite a bit. And it can give you a short breather when you are feeling overwhelmed.
I'd also recommend watching some old "My Cat from Hell" episodes, they have some very specific advice that can help out a ton! Jackson Galaxy is really a cat whisperer, and also talks quite a bit about the relationship between not only the humans and the cat, but also coaching the relationship between people as well. It's important you and your fiancee are on the same page and work together.