My husband and I have been together for 13 years after knowing each other for only 9 months before marrying (and I met him online). I think what makes us successful are the following (in no particular order):

Conversations: we talk about everything - big, small, interesting, uninteresting, important, nonsensical. There is rarely a time when we are together and not discussing something. I mention this I think because when we go out to eat, many times we see couples just sitting across from each other totally silent. I think it's a bit odd.

Sharing activities: it is important to share an interest in similar things. one of the things that drew us together was an interest in science fiction movies and literature. And while we don't necessarily like the same Scifi we do have many in common where he can suggest readings to me and I can to him. We have since discovered many other similar interests.

Appreciating differences: he has some hobbies that i'm just not interested in and he is welcome to go off and do them on his own occasionally and i can go off and do my things that he isn't interested in. He likes certain strategy games played in groups that i don't really care for and I like shopping and some other hobbies that he doesn't care for. However, there does come a point where too much doing of one's own thing becomes a distant relationship which is why the word occasionally is there.

Sex: being able to say yes whenever and everyone is happy; but there are times for no as well and being able to say no without the other person thinking something is wrong - sometimes there are just no-times in life which should be allowable for both (too many no's though and probably something is the matter). Sex drives change over time - they ebb and flow - of course hopefully more flowing and less ebbing.

Not playing 20 questions (I guess another word for this is trust or control): I trust when he tells me he is going someplace that is where he is going and vice versa; i don't grill him about his every movement and he reciprocates. Nor do i call him 20 times a day to find out what he is doing. When he is at work he has things to do and we speak maybe once or twice a day. The same for my work day. I have a problem with people who have control issues (this is true for women or men).

Being able to let things go: everyone fights - the key is one person or both parties being adult enough to say - you know what - i need to step away and not deal with this until i cool off. so many couples i see like to have the knock down drag outs (not physically but verbally) until one person passes out from lack of air i guess. i think the theory is the louder you scream the more the other person will listen to you; however the opposite is usually more true. When i am very angry i do not like to talk to him until i have calmed down enough to discuss the situation rationally. I grew up in a household with what seemed like constant screaming and i hated it then. He understands this and we do not allow that kind of irrational behavior in the house.

I can't think of anything else at the moment but these are some of my big issues i think.