As a key theme, your other half (wife/husband) should be your best friend.

And here's an interesting reflection on the core of love, from Louis De Berniere's book, Captain Corelli's Mandolin. The wise old Doctor Lannis is advising his daughter Pelagia, who has fallen deeply in love with Corelli:

Love is a temporary madness, it erupts like volcanoes and then subsides. And when it subsides you have to make a decision. You have to work out whether your roots have so entwined together that it is inconceivable that you should ever part. Because this is what love is. Love is not breathlessness, it is not excitement, it is not the promulgation of promises and eternal passion...

That is just being "in love," which any fool can do.

Love itself is what is left over when being in love has burned away, and this is both an art and a fortunate accident. Your mother and I had it, we had roots that grew towards each other underground, and when all the pretty blossom had fallen from our branches we found that we were one tree and not two.