Lack of having sex for extended periods of time.
Man: Too long. I'm drivin the struggle bus
Friend: Dude it's been too long, you're being a bitch.
Man: I'm strugglin
Someone who has a lot of issues or problems. Often these issues interfere with the person's ability to behave normally.
Sarah: What's wrong with her?
Jennie: Her family is messed up and she has no friends.
Sarah: Oh, that's sad.
Jennie: Yeah, she's got struggles.