There was another alien species that was invading Earth, and the little furry aliens helped us out. I think they liked having sex all the time and ended up having sex with the humans as well.
1 Answer
Might you be talking about Allen Dean Foster's Quozl?
The Quozl knew they'd love the third planet from the sun. But it never occurred to them that anyone lived there...
The eponymous Quozl, based off of rabbits, have a stereotypical fixation on constant sex, and indeed, part of the ending indicates that they have no problem with humans being the target of this behavior...
story-identification
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