Personally I fail to see how this could become a mood killer, unless the couple tried to pursue other cples that obviously were not interested.
At all the parties hubby and I have attended therr have been people that wore different clothes than us, was older than us or we were just not attracted to in general. Yet it did not "kill the mood" for us.
Wouldn't say you were being intolorant, but possibly just bored at the party, otherwise you might have been too busy
to notice them.