First thing to keep in mind is that, ur partner and the members of ur family are different, unique people. They tend to have their differences. Our partner and us will have differences. We try to accomodate and move along with these differences.
If the family cannot tolerate the differences and cannot adjust, then we try to ask our partner to try and do so. If both parties cannot stand each other and both aren't ready to compromise, then we have to compromise.
They are not bad people, both our family and our partner. It can happen that they won't get along, it doesn't mean we choose one and let go of the other.
Family is where u grow up for years and years (mostly mid 20s) and the life partner is someone whom you try to grow old with. Both have their significance.
If we leave one while we get the other, the same will happen to us when we get old.