i would definitely ask her first. it doesn't sound like she'd mind, since she's already moved on, but you don't want to risk the friendship do you? So clear it with her and then go have fun with him!..

I think you shoudl ask her first...Mention to her you've liked him for awhile and remind her she broke up with him. However, let her knwo you value your relationship more than anything and would appreciate her honesty...I do not see why there woudl be an issue, but I do think you need to ask first...Good luck!..

If you're really close friends with this girl, you might want to run it by her first. Because, whether she dumped him for someone else or not -- she's likely to get pretty pissed off that you went after her man...