I find Odin makes sense, to an extent, cause the heart wants what the heart wants.
Now time for a personal anecdote:
A couple of years ago, I was in love with a guy. He fell in love with my best friend. My friend, asked me for permission before they started dating and it has shaped my opinion on these types of situations ever since.
There is basically no point in asking. Whether it's your friends ex, the guy/girl they've been trying to hook up with for years, or the love of their life, there's no point in asking for permission.
When I was asked if it was okay, I said yes. Because, am I really gonna say no? Am I really going to be that big of a bitch? Am I really gonna try and keep someone else from finding their happiness cause it's not with me? Is my saying no really going to stop them? No. And if for some reason, it actually did, would I want to live with that kind of guilt? What if they were fuckin' soul-mates or something? You can't know.
Now, when my friend asked me, it was a nice gesture, and it did make her seem like she was being considerate. But I don't for a second think that she wouldn't have dated him if I said no. And that's okay.
Did it make things awkward for a little while? Yes, cause I had serious feelings for the guy my best friend was now dating. But, it actually helped me get over them, knowing he was no longer an option. And it was nice seeing two of my best friends happy. If it had been my ex boyfriend who I had just broken up with a month or so ago, it still would have turned out that way. Part of you doesn't want to see someone move on faster than you, but if they've moved on to your friend, and you know your friend will treat them right, if you still care about them, that turns out to be a good thing.