Is it wrong to have a crush on your best friend's ex???
Honestly, it really sucks for your best friend. One of my closest friends actually started to date my exes (without permission) and to say the least, I was about to punch her down into the core of the Earth.
There's really no right and wrong thing to do, unless if you just stay silent about the matter and don't act on anything. That's probably the best thing you can do in this situation.
If you do act on one your feelings, know that whoever you choose, the other person will drop you.
Then chances are, your best friend won't want to talk to you anymore. Good luck.
she knows though i asked her permission and we've been dating for three weeks.
…right. Then why did you start this forum 4 hours ago?
because I was worried my friend seems distant and zones out all the time.
well she probably secretly doesn't like the fact that you're dating her ex. You know. She dated him and yet, you ended up being with him. And maybe she's going through something else. Maybe you should actually talk to her and see what's bothering her.