My new girlfriend’s grand-father just died. I want to skip the funeral because I haven’t met her family yet. Mistake?

No, it sounds like a good call. While they might appreciate that you’re offering a shoulder to cry on, a grieving family isn’t in the mood to entertain a new boyfriend. Don’t fabricate an excuse. Say, “This is a time for you to spend with your family. I hope to meet them soon, in happier times.” Then send an epic bouquet of lilies and be there for her when she needs you.