My fiancé's cousin met and started dating someone since us getting engaged. We're under the 6 month mark and have already sent out the save the dates. Just this week I was told by a third party that they will be moving in together "soon". I don't know what soon means. There is only one other guest which a boyfriend is in invited, the other guests' significant others are engaged or married. Their relationship has escalated quickly, she has had "serious" boyfriends before, and save the dates have been sent - am I required to invite her boyfriend to the wedding? I've never met him and my fiancé doesn't like him.