@natsnorigin Do either of the cats have the "Territorial" trait? Or do they have traits that conflict with each other, i.e. Affectionate vs Aloof, Frisky vs Lazy? I have never quite been able to figure out cat behavior in Sims 4 (much less cat behavior in real life) or why sometimes they won't get along, but I've always suspected things like this.
The easiest thing I can think of trying is to use testingcheats and cas.fulleditmode to change their traits to "Friendly" and to remove any conflicting traits they might have with each other.
If your main goal is to have kittens, you can also use the cas.fulleditmode cheat and go into the CAS screen and choose the Add a Sim and Play with Genetics options (with both of your cats as the parents) to add as many kittens as you want, as long as you do not exceed the 8 Sims per household limit. You can randomize the kittens so that they don't all look alike.
Good luck I hope some of this helps. Cats can sometimes drive me crazy on this game too.
#stayandplay
