I hate this argument. Even for us, who ARE mortal, our lovers will die before us or vice versa, save for the more likely break-up or the highly unlikely tragic accident/disaster.

We love our pets "infinitely" too, even though we know we'll see them die. Those who have the most pets have seen dozens die. I don't know of anyone who lost the ability to love their pets as if they never would because of that.

For these reasons, I strongly believe "immortals" would love just as intensely as ephemerals, if not more; and that they would indeed take a long time to rebound from loss.