Noun, psychological condition.
1. Someone constantly finding or causing problems in an otherwise good relationship, in an effort to gain attention or sympathy, or because their standards are too high.
2. Someone dating people who are bad/wrong for them to create conflict. Out of stupidity or self-loathing.
"Did you hear? Joe and Sarah broke up"
"Yea, she's got relationship munchausens. They do this every couple of weeks then get back together a few days later."