Lots of good advice here! DH & I married later in life & had already seen friends & family divorce. Maybe that helps us, maybe not having kids removes another kind of stress.
Laughter and respect are important. If something is important to me, DH makes it important to him, even if it is something 'dumb', if you know what I mean. And me with him.
I did read something a few years ago that made sense...some of the things that attract you to your mate will later drive you crazy. It's hard to explain. Like if your mate is spontaneous and likes to plan sudden weekend getaways that you love. The reverse of that is they're sneaky. THat's a poor example, but maybe you can understand what I'm trying to say.