Have better sex, and more of it.
Sex isn't just a carnal pleasure, it's a way for two people to connect. In a relationship, sex is just as important as communicating or spending quality time together. You could even argue it is quality time together.
This year, committ to getting more naked one-on-one time. Presumably, your partner is the only person you get to have sex with. So, make the most of it. Make it your aim this year to appreciate the gorgeous woman in your bed, and give her plenty of that sexual healing only you can provide.
Out of all of your resolutions, this should be the easiest one to keep.