im afraid there is nothing more to it than what is stated...
3) I am not friends with them, but acquaintances, they are friends of a good mutual friend of mine - a few times a year they are out with a large group I am also out with..............this would mean I would have to sit there and pretend all is fine
4) Following point 3 because we have a close mutual friend I know full well she is 'really into him' and 'loves him with all her heart', it's known that she adores him............this just makes me feel more uncomfortable and do an epic face palm because she's just getting walked over
Ah, so there is more to it then!!
You want your mutual friend to be with the gf because you think they'd be a better couple/happier together, right?

Oh no, he must have some hidden agenda!!!11111
lol