A friend wrote to me recently, saying that they've realized two very important things from their recent experiences:
"Now I know how absolutely important it is for someone to feel a) not lonely; b) like they are being respected by people around them."I think that the key to both comes from understanding. Unless you understand someone, it's hard to respect them; and more seriously, one of the biggest drives people have in life is to not be lonely - and people feel lonely when they are misunderstood, but not at all when they are understood.
I don't know how to weigh being understood against all the other factors that matter, but I think that's it's one of the biggest keys - in life, in marriage, in respect. Find someone who understands you - really understands you. If they do, a lot of the rest becomes doable.