Why do you hate your boyfriends ex?

Answer 1

Because it's a natural thing to feel hate and jealousy towards an ex!

the fact he/she had your partner at one point can make "you dislike the ex"

It's a territorial thing and very natural.

I agree with the first answer. You know that your boyfriend once had really strong feelings for his ex, they were intimate, shared a life basically.

But if you hate his ex because you think they're way more beautiful, perfect or whatever it is, remember this; if they were more perfect than you are, he would be with them. Their relationship ended for a reason, they weren't right for each other. You're with him now and that's the important thing. There's a reason he chose you! But it's very normal you don't like his ex, trust me.