Threesomes will they make or break a relationship

Brittany

So my boyfriend wants a threesome ( well ex) but we are still friends hang out everyday and talk everyday, should I give it to him? I have never had one before and don’t mind doing it to make him happy and spicing things up. He told me I don’t have to do it to make him happy but I always think of his happiness. Has anyone done this and how did it help with your relationship.