By "do so little for you" it really means someone who doesn't meet emotional needs you have deep down inside, reciprocate your love or service, or let you know you are deeply cared for - NOT by our society's means either (i.e. material things) but doing it in the way YOU genuinely respond to.... I have love to give regardless of my well being....Period
When I was younger I would have said that thad mad passionate part of love never leaves and if it does, the relationship is doomed. After 31 years of marriage, I know there can be moments of the madness, but you'd be a burnt out shell if it continued at that level year after year. So, the mature me, who is still madly in love says it's a nice, exciting balance of both.
You don't 'fall' in or out of love. Love is not a ditch, it's a choice and a commitment. To love is to keep the greatest commandment. CHOOSE to love that person, and then with God's help, do everything in your power to create a loving atmosphere.
We all need to remember to be thankful for those in our lives while they are still there. Everything can change in the matter of moments and the pain from that only comes from the regret of not appreciating what you had while it was yours.