With the anger that can accompany some breakups — or if she's had a number of bad relationships in a row — she might try to convince herself that all men are bad. With that mentality, she won't need to invest, trust or develop an intimate relationship with anyone again. But it's not healthy, and it doesn't acknowledge that relationships are made up of two people. Even if he was the worst guy possible, she had her own contributions to what made the relationship not work (even if her only "contribution" was ignoring red flags, staying too long, or allowing herself to be in a disconnected relationship).