Worst love interests

I got the idea for this question since I’ve been reading so many comments on Jinx.
To be clear, I’ve never read the series, so I cannot make any informed opinions on it, but it did give me the idea to ask, who has been the worst, most toxic love interest you’ve ever seen?

Originally I was going to leave it as only the worst ML in BL, but decided to open the question to any love interest.

Additionally, only characters that are supposed to be taken seriously as love interests.
What I mean is, for example I don’t think Killing Stalking or Placebo are supposed to be considered romances.

Now, for the worst love interest I’ve ever encountered in any story, hands down it has to be Richard Tarten from the Passion sequel. This character is nasty, and the romance pissed me off to no end. If anyone has read the novels, I think many would agree.