k. d. lang has a song, "Simple." The whole concept of the song is that love is simple. People try to make it too complicated.
For me, I just try to follow a few simple rules, and so far, it's worked just fine.
1. Keep honesty as your basic principle. Sometimes, honesty is not the easy way to handle something, but it is always the best way.
2. Adhere very strictly to the "Golden Rule." Treat your partner as you would choose to be treated. If you like getting flowers, give them once in a while. If you don't like to be yelled at, don't yell. If you don't like to be lied to or cheated on, then don't lie or cheat.
3. Keep it fun. Laugh together. Get up early on your mutual day off, tell your partner "get dressed in comfortable clothes, we are going for a drive" and go to a surprise location that you don't tell your partner about, and spend the day... one very memorable excursion for me was a trip to Annapolis, about an hour drive.
4. Never let it get stale.
5. Do not try to change your partner. It won't work, and it just frustrates and angers everyone involved. That's one of those "should have thought of that before you hooked up" situations. If there's something about your partner that's annoying, talk about it. If they don't/won't/can't change it, learn to live with it. If it's intolerable, you don't belong together. It's much easier to choose someone, in the beginning, with whom you can spend your eternity.