My (F) partner (M) Aspen has developed a rather obvious crush on my best friend Birch's fiance Cedar.

He tries to engineer opportunities to see her, private messages her, follows all of her socials, constantly asks if we can go do things with them etc. He spent a sizable amount of money trying to win a collectable figure she was after from a blind box figure set she and I both collect.

Aspen's family have even brought her up on several occasions with comments like "so when do we get to meet this girl?" or "oh isnt this Cedar's favourite character from the movie?" which tells me he has been talking about her to them.

Birch and Cedar are completely monogamous.

I truthfully find it a bit distasteful and fairly disrespectful to Birch. Birch is like family to me.

I havent directly mentioned this to Aspen, Birch or Cedar but I also dont know if I should just ignore it as an innocent crush? Thanks for any thoughts that might help me determine if I need to say something.