I fear I post in here a lot, but I need an opinion. My sister and I have cats: one neutered male cat and two kittens, one a boy and the other a girl. When she got them, the girl was given to me. They are 5 months old now and in heat. The boy has been mounting the girl and stuff. We tried separating them by putting one in the carrier and leaving the other out, but when I did this one day, the boy tore through it because his claws haven't been cut. I tried keeping the girl in my room, but she just yells all night. I pulled out their playpen so that one could be in that. I put a bed, litter box, food, water, and some toys in there. This whole time, I've been trying to figure out what I can do until they can get fixed. My sister just keeps saying, "They're animals, and they're going to do what they want to do; we can't stop them, and I'm not stressing myself out about that, and how she doesn't want them in her room because they've been marking territory and how I'm just stressing myself out. Being in heat is painful for animals. The act of mating is even more painful for females especially cats and that can lead to her getting pregnant and while I can still get her fixed therefore terminating the pregnancy I would like to avoid that if I can. My sister's dismissiveness is frustrating me because I feel like I'm doing more to prevent this than she cares to. Taking on these responsibilities is fundamental to being a pet owner on top of the imo. Am I wrong for doing all of this? or the asshole for being frustrated? (I should also state that I work at a pet store, and one of my coworkers informed me that I was doing the right thing by keeping them apart, but I don't know anymore. She also said she has enough to stress about, so she isn't worried about them right now, and finally, she was saying how he'll probably tear through it when he was in it, though I was confident he wouldn't because he was having fun and enjoying himself. She said this because of the carrier incident, but the carrier was small, and no one would want to feel trapped.)