So I didn't actually read this but someone posted about it and I thought it sounded good. I thought that it was on this forum but I couldn't find anything in my searches.
Anyway... The H is older and the uncle of the h's best friend. They meet at a wedding, I think, or maybe end up having a one night stand later that night. The poster who rec'd it mentioned how it was refreshing that it wasn't a big deal to the niece that they get together.
Hoping it rings a bell with someone! I've already spent waaaay too much time trying to solve this on my own. Thanks