For those that are married or dating:
Would you have married your significant other if their family hadn't liked you? For those dating, would you continue to date the other person if their family didn't like you? Why or why not for both.
In my case, and I've written about this before here, my mother-in-law was (and still is to a large degree although she's gotten better since her heart attack) a very possessive, power-hungry and manipulative person who didn't have anything against me, per se, but was dead against anyone intervening in her relationship with her daughter (my wife) even though she had done most everything to destroy that relationship in the prior 10 years or so. My mother-in-law is of the mind that she, and she alone, is the only one who truly loves her daughter and knows what's best for her in all
things even when she's outright wrong about them.
In the end, I stuck it out and pretty much ignored her little games, much to her dismay, although I did fall prey to one on the day of our engagement, but that's another story for another time. Nowadays she has calmed down quite a bit once power was wrested from her and she realized that I'm not what she was afraid I was (my wife had a bad dating record, to say the least) and we get along, although I'm still far from enamoured with her treatment of her daughter.
In short, you don't marry the family, although in some cases it may seem like it. As St. Paul wrote, love conquers all, even crazy relatives.