When falling in love, make sure you’re not also mortal enemies with his family. If it seems like killing all his relatives might be a possibility in the near future, perhaps rethink that second date.
PS. This is a very important lesson and applies in more ways that one. You might also consider checking to see if you have at any time ever killed their spouse or other close member of their family… Or them, in a previous life. (See: Goblin, Bad Guys)
Real lesson: In-laws can be scary, guys. And no, your parents might not like every guy you ever bring home. Maybe have a plan B “how to break it slowly” before you announce wedding bells?