Great thread!
I also see huge red flags here...
1 Not feeling comfortable to express what you really feel
2 Money, if he goes, is that HIS money we are talking about.. ?
3 Walking on eggshells, now it is this bachelor party, then what will it be?
It looks like there are huge trust issues...
Do you know the people he is going with..? do you consider them your friends, as well?
Hugs, not an easy position to be in....