Healthy grown up love to me is a lot about friendship. Cause after the honeymoon phase wears off and the relationship progresses, the physical goes through cycles of attraction. The passion goes through cycles too.....it never goes away (or shouldn't) it just hibernates for periods of time when "life" takes hold.
Its during those waning periods that the relationship grows roots, and deep, lasting love. its friendship that will always carry a relationship because they are all hard, and all suck at some point and time. Like Anvil said, sometimes I want to kill my husband, but I would never hurt my friend. Sometimes I'd like to get a divorce and be single, but I can't be without my friend. Then the moon rises again, the love and passion kick back in, and I am madly in love. Its pretty cool.