Helene was saddened to learn that Popaul was the killer, but perhaps even more hurt about a life, any life, gone awry. I think that she was showing mercy to Popaul by acceding to his request for a final kiss. More than anything, she wanted people to be good. She loved him, but not as deeply as Popaul loved her. Great, great movie!
I think she was fascinated by Popaul. She was both, terrified and uber-excited by "the butcher". She "desired" him and at the same time "feared" him.
IMO, had not Popaul commited those crimes, their relationship would have remained strictly platonic, basically because Hélène wouldn't find Popaul (the butcher) interesting enough.
It's the feel of danger what attracts her to Popaul. It's her stoicism, determination and purity what attracts him to Hélène. They both were meant to desire each other and perhaps even to love each other, but they weren't meant to end up together. No "happy ending" was possible.
'Le boucher', is one of Chabrol's finest films.
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