from where i cheat:
you and dh are very good friends with john. you and dh go on a trip with john and his girlfriend, jane. you do not feel well and bow out of part of the trip. later, jane sends you an email saying that she does not appreciate how you ruined the trip for everyone.
jane's behavior continues in this vein for some time -- gtgs with john and jane, sometimes followed up by nasty emails from jane, sometimes to you, sometimes to dh. eventually you and dh tell john that you wish the two of them well, but you will not be spending any more time with jane.
john and jane get engaged. jane sends you and dh a long letter, apologizing for all of her bad behavior. she accepts all responsibility for how bad the relationship went, and for damaging the relationship between you two and john. you and dh accept, cautiously.
john and jane would now like to be "couples friends." they would like to gtg.