Even though it's treatment of the subject is darkly comic, I'd also nominate Roman Polanski's "Bitter Moon." It's a nasty, hilarious, disturbing film about a couple who basically lost their minds following the relapse of a compulsive sexual relationship. Peter Coyote and Emmanuelle Seigner play the couple, Hugh Grant (perfect casting) plays the aloof married man they tell their story to. It has a very cheesy Vangelis score, but it's a solid script, the actors are having a ball, and some of it is pretty disturbing (especially if one of your fears is paralyzation).
I'm so glad you mentioned this one, Dylan. It is absolutely one of my favorite films of the 90's and possibly even my favorite Polanski (though this is an understandably tough call). Grant is
perfect here but so is everybody else and, really, Coyote is beyond brilliant in the pivotal central role. He has a very tough job in selling us pretentiousness and self satisfaction and bitterness, of course, but never overselling any of them and his performance is a finely tuned thing of beauty (Coyote, I fear, will be one of those actors with great potential who was never allowed to have a fully realized great career and certainly was never recognized in his time--except for voicing ads for Chevy or whatever). The scenes between he and Grant in which he very carefully calibrates the delivery of his story to guide Grant's reactions are exquisitely handled. And, yes, it is all undoubtedly disturbing because it nails Grant's personality of passive rationalization and self-deception; Polanski understands what would seduce him just as Coyote does. The ending never fails to have the intended devastating impact even if it is no longer "daring"; actually, its superficial provocative quality is ultimately secondary to what it means
as is always the case in successful art of this sort. Whatever the case, this title has entered the vernacular for my friends and I. Whenever anyone suspects that their relationship may end with that little additional knife twist, it's a "Bitter Moon Moment" we want to avoid.