Would you makeout with your MLM bestfriend???

I’ve been going out with this girl (gold star masc) for 2 months exclusively but not officially. I found out through a mutual friend that she has recently madeout with her gay (mlm) best friend and that this has happened in the past as well. Apparently it’s platonic because they’re wlw and mlm so they aren’t attracted to each other? what the fuck? how would you approach this?

Edit: Exclusive as in we have both told each other we aren’t interested in dating anyone else. Not officially as in we don’t have labels (girlfriends) currently.