Does anyone have any experience with having a crush on your partners best friend? My partner knows, I was just wondering if anyone has any similar experiences that have worked out positively and if it didn't work out, why?
Since I never really "dated" and tend to only interact with new people if they are already friends with my (limited) circle of friends, most of my sexual (and romantic) partners have some sort of relationship with each other. (When all of us were in the "marrying phase" it was a standing joke that we would pass the time figuring out how many of the guests the bridal party had slept with

) I met MrS and his best friend at the same party when I was in High School, his friend asked me out and he asked out my friend

. (Only took me 4 months to sort out that "error" - which involved me taking my friend's ex-BF to the Prom so that another guy would go with my other friend. JEESH

).
Having said that, you're keen to see what others have done to open up romantically to a friend of one's partner - specifically a best friend.
Jane has been quite liberal in sharing
her story, so I think she won't mind me sharing it. Start from post 19 I think. Jane quite candidly says starting the relationship as an affair is the wrong way to go and very bravely shares her experiences with us to learn from. I respect Jane a lot for her candour and personally felt I learnt a lot from her story.
I'm Jane and you may certainly share my story. If anyone can learn from my mistakes then posting it online was worthwhile.
Dude was MrS's best friend for several years before I even met him. (If this seems odd to anyone, it isn't for us - I work long, long hours interacting with people, but, as an introvert, this is draining for me. When I am home/off meeting new people is at the bottom of my list of ways to spend my time.) If MrS invites someone over then they must be REALLY GOOD people (I hate having "strangers" in my space.)
I never intended for anything with Dude to go past the "flirtatious wife" level...but it did...and I handled it poorly (as you can read in the link above - I was a complete Jackass). Things turned out to work out for all of us, but I think that was dependent on SOOO many factors. For instance: MrS's trust in me - I broke it, but that was ONE mistake not a serial event. Mr's ability to forgive. Me holding myself responsible for my own choices. Dude's love for both of us. I wrote about this in the
Trust Broken...and ReBuilt thread I started a few years ago.
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With that preface - IF it is a "cheating affair" situation (like mine, for the most part) THEN I think that likelihood of a happy ending (like mine) must be extremely rare. I was fortunate in the people involved. But recovering from your partner and your best friend betraying you at the same time, with each other? That is harsh.
On the other hand - if everything is above board and NOT a cheating situation? Your significant other is aware (and, I assume, supportive?), if the best friend is willing? Well then you have a cohort of people who actually care about each other and don't want to see anyone hurt. I think the elusive "compersion" is actually easier to achieve in this scenario. (I know that, for myself personally, I am MUCH more comfortable when my boys are attracted to and involved with people that I admire and respect, especially if I have any sort of relationship with them.)