Young swinger looking for advice

Hello! My girlfriend (33) and I (24) are in swinging lifestyle for about year and a half and I have one problem - on events with a lot of couples around I can't relax myself and it takes too much time for me to get erection. It is interesting that I don't have that problem when we are with only one couple, only with multiple people around.

How can I relax myself in those situations? Could those erection gels help?