Having established they are indeed boyfriends and want to make going all the way special, I think the story could be reaching a climax very shortly...say in the next week?
I actually think Tristian is somewhat entitled in his acceptance of concealing his orientation. Having said that I think it's everyone's prerogative as to whether to publicly acknowledge their orientation, however when you are in a relationship, the other partner must be on the same page which I doubt Tristian even considered....
I too think the timeframe is in the early to mid-eighties.