I think a line can - and usually is - drawn in most workplaces between appropriate and inappropriate discussion of relationships. Referring to sexual acts with one's partners is inappropriate. However, saying that you saw a ballgame with your wife/husband/etc. is safe and inoffensive. The point I'm trying to make is that being openly homosexual just means you're honest about the pronouns you use when describing the person you went to the game with. To reiterate: When a man says "I saw the game with my wife." he's openly heterosexual. This is not forcing his sexuality down anyone's throat, this is common, everyday behavior.
So, to beat this point until it's dead, problems arise from the topics being discussed, not the people mentioned and inferred (or explicitly stated) relationships of those involved in the discussions.