Been married for 35 yrs, but almost crashed and burned at 12.
I discovered a few things that work for me and are generalities, I believe, of most women and men in marriages.
Men want to be respected, and women want to be loved.
If she doesn't respect you it will emasculate you and you'll go elsewhere for that respect. Likewise, if you do not make her feel loved she will resent it (you) and may find it in other places.
The phrase "Happy Wife, Happy Life" sounds trite, but if you've been around for a while you know it's true. So how do you really make her happy?
I heard somewhere that every girl longs to be desired, to be "the one". I think it's absolutely true. It's in the DNA. Why else would women 90 yrs old get their hair dyed and put on makeup?
So, the key, I think is to make them feel like "the one" for the rest of their life in whatever way relates to them.
You need to also let them know how you feel respected and if they are a keeper they will do that for you and you'll both be happy.
On the other hand, if they are crazy, run the other way as fast as possible ,