I vote for going for it. He doesn’t own her future, or yours.
ok so yea I’m gonna go for it.
Do I talk to him first or just go ahead with it.
Cause a friend of mine used to always say, “It’s easier to ask for forgiveness than permission.”
It’s easier to reset the broken nose he’ll give you if you ask him first than to reset your legs when he breaks those after finding out himself.
Hey, nothing like a happy send-off, right? 
Where?
Stranger
Convents.
This is what happened to me:
I met “Betty” years ago, but interacted with her very seldom for 3-4 years. During that time, she started dating a guy, “Barney”. They were an item for 2-3 years, and some of that time lived together. (NOTE: we all work in the same industry.)
About a year, maybe 18 months after they broke up, she started hitting on me. I, of course, eventually took her up on her offer. I caught some flak from people that Barney knew well, who really didn’t know me all that well.
Eventually, one guy “Fred” and I were working together and the subject came up. he gave me all kinds of grief about it (altho he and I got along well, he was explaining his reaction, and why people gave me grief). He finally said “…but Bo, you don’t date you’re friends ex-GF or ex-wife; it’s just rude and something you don’t do!”
I looked him straight in the eye and said “Fred, Barney and I aren’t friends. Never have been. He’s just some guy I see at work when we happen to be on the same gig.”
“What? You mean you aren’t buddies?”
“Nope. Never have been. We’re friendly at work, but we aren’t friends.”
“Oh. Well that’s different then.”
Other than a handful of people with the wrong idea about our mutual relationships, I never heard anything other than “oh you guys are dating? Right on” from anyone.
And I wouldn’t ask his permission, but to ask him point blank whether anything is between them is fine. But I wouldn’t let whatever he says interfere with my plans to ask her out, IIWM.
Good luck! We’re all counting on you!
Is she the last woman on Earth? Then it’s OK. If not, don’t do it.
All of the algebra really comes down to the single question of how the dude is likely to feel about it (and how much you really care about how he’ll feel about it). If you think it will really bug him, don’t do it, if you think he won’t really care, then go ahead. There aren’t any other rules you need to worry about.
Go for it. In a few months you’ll both be able to bitch about her over a beer. 
Well, I did it. We’ve been married 10 years now, and I never stopped being close with the friend.
What helped was:
- it had been a few years since they’d broken up.
- friend was seeing someone else quite seriously at the time we got together
- friend had never been serious about spouse
- friend cheated on spouse
Each situation is different.
Feh…I married my best friend’s (actually my ex-sister in law’s) ex husband. Each situation is different. If you’re considering “going there”, you need to weigh the consequences and do what you think you can handle with regard to possible broken relationships.
I also pursued a relationship with another friend’s ex. That one didn’t go so well. 
It’s a crap shoot.
If the situation is really like what you’re describing in your second post, Scotty, I don’t see much of a problem with it. You’re not really friends and they’ve broken up for awhile. If the guy gets upset, even gets upset at you, what he’s REALLY getting upset with is the opportunity he’s realized he’s lost out on. That’s not your problem.
My fiancee is the ex of my friend/guy I worked with.
We were at a party when I met her. I knew they dated in high school and she is his best friend. They dated years ago, with history good and bad, but they are really close now.
I asked his permission and he said he didn’t care as long as I wasn’t a jerk to her.
Things haven’t really been awkward. He seems happy that she’s finally found someone decent, although every once and a while he’ll forget that she’s engaged to me and he’ll say something inappropriate. Not like he’s hitting on her, just something you don’t say to your friend’s fiancee.
It’s worked out so far.
Yeah, but their boyfriend is a lot more jealous.
Ew. You married your brother? Kinky. 
I agree. Since they are in the same “circle” but not really friends, the only bad consequence might be that your mutual friends could feel uncomfortable…but from what I know of guy friendships, this isn’t really a problem the same way it is for girls.
My ex-bf dated a common friend a couple years after becoming my ex. For some reason it made him nervous, but neither the other woman nor me had any problem with it. He’s a nice guy and I thought they actually were a better match than he and me.
Just after college, I started dating my best friend’s ex. I knew that best friend was now dating someone else, and we were all 3 members of an extended circle of friends.
It worked out well for me. He’s been my SO for 18 years now.
But…
- I knew that best friend had moved on.
- Best friend and SO were still friends. No hard feelings.
- I wasn’t just looking for a fling. I probably wouldn’t have risked upsetting my best friend for a few nights of wild monkey sex.
I did give my best friend a heads up of what was coming, so it didn’t seem like I saw sneaking one over on her. I asked her permission to date her ex, even though we both knew I didn’t want or need her permission. It was just a way to let her know.