For women: take care of yourself, try to look as good as possible, shave your fucking legs (men are visual animals, deal with it), don't nag him, make him a sandwich, and fuck his brains out.

For men: take care of yourself, try to look as good as possible, buy her flowers and candy, listen to her stories, care about her feelings, and fuck her brains out.

For both: add spiciness to fucking, try different poses, play roles. Don't look at anything as a transaction, do it from love; love your partner, do things that make them happy.

It's that fucking simple to live happily ever after.