What is it with "unconditional love," anyway? Why are humans so fascinated by this notion? Is it because they feel so inadequate that they can't imagine actually deserving or earning love on a day-to-day basis?
This phrase comes up all the time when people talk about why they love pets, which, they say, give unconditional love. I am dubious of this. It may be true that what dogs and cats want is straightforward and not hard to give them, but I think they certainly have conditions. Try starving your pets and beating them every time you see them and see how long they love you.
I do understand that love should have a long-term arc that transcends the feelings of the moment. Our children need to know that we love them even when we are angry with them. So do our spouses. But that is not the same as "unconditional."
Love between grown-ups should have more in common with friendship than it has with parenting an infant. Love between grown-ups should be based on mutual respect. It should be based on expectations that our partners will carry their own weight in the world, be pleasant companions, and keep the promises they have made. Not all the time -- everybody falls low at times, and everybody screws up, and the long arc of love should keep our partners with us for a while. But to expect to be loved as a baby is loved, without having to do anything to earn it beyond an occasional smile, is to deny both the responsibilities of adulthood and its greatest joys. One of those great joys is to earn love through our efforts and because of who we are. Love should not be brittle, and we should not fear losing it because of an act or a word, but love worth getting is given because of what we give in return.