You say, for instance:
A mere month ago, it seemed they couldn't get enough of each other. My, how things have changed after one big falling-out. Now there is no/little love lost between them.
This expression might not translate easily into other languages. It is an understatement, a heavily ironic way of saying that, given a mutual dislike, animosity between two people, "any amount of love would be lost/wasted on them". Basically, they can’t stand the sight of each other, making no effort to conceal it. It's as if to say, there's only so much supply of love, like time, allotted to each person in their lifetime, so no sense in wasting any of it where it is not needed.
How is this idea commonly/idiomatically expressed in Russian?