We got a new cat (male 1yr old neutered, Milo) 2 weeks ago and have followed all the advice, ie separation from existing cat (female 3yrs old spayed, Cassie), scent familiarisation which we thought went pretty well if slowly (Cassie ignored it most of the time, ie walked away from anything with his scent on it). Once she started tolerating the scent, ie no hissing or visual aggression we then went onto next stage, visual familiarisation, which did not go very well. We went back to scent again and after another few days tried visual again with same result, it got a bit worse, her being extremely aggressive, hissing, trying to claw through crack in the door. Milo has now been kept separate in our spare room for 2 weeks now which I feel is too long. He is very affectionate and I feel bad keeping him locked up but Cassie will just attack him (again). Am happy to keep going with the scent, visual, swapping rooms etc but my worry is Milo being kept in spare room alone for most of the day (we both work) with no company. How long till it is just too cruel should he be shut in one room alone?