Well tbh, threesomes can be tricky things since it really depends on who the third person is. If Malkai and Catarina are like how they were in the last one, he might not like it since he doesn't really like Catarina. It's not that she's ugly or anything, but she's a bit... Loud. He wouldn't like having a relationship with Vivian, but she's still a mystery to him, so she isn't good or bad.