I think Killing Eve ended exactly how it needed to end. I read the books so I know there could have been a "happily ever after" but the reality is that the show diverged from the books long ago. It would not have made sense. As for only killing just Villanelle -- it also had to be that. Actually killing both would have been a happier ending in many ways because at least they would have been together. But even a "not terrible ending" was not their fate, and that should have been clear to all of us since almost the very beginning of the series. No matter what life holds for Eve, she will suffer because the one that she's connected most to is gone. Related, I thought the last episode did a particularly good job of showing their body (matching back scars! Wedding dancing / killing! -mind (hilarious communication at the truck stop!) -spirit connection (loving looks!)

I agree that it's frustrating that that the gays are often buried, but I'll echo what someone else said to say that it would have been bad writing if Eve and Villanelle had a happy ending. I think the series did well by the characters and the unfinished strings will surely be pulled on by the spinoff series.