When you say "I don't know if..." there is an implied "or if not." In this case, the sentence means "I don't know if [the reason for my problem is] my bad choices in men, [or if the reason for my problem is something different]."
A simpler example:
"I don't know if I'll go to the party" = "I don't know if I'll go to the party or if I won't go to the party."