One of his first appearances in "Members Only" (aka Guys' Night Out) had him confiding in Angel about how he seemed to either be invisible to women, or easily glossed over as soon as they saw another guy, and that only other guys and lesbians seemed interested in talking to him... only to then realize that he's sitting by himself.
It's come up again with this strip. Chris mentions that he's stopped hanging out with Jim because Jim can't stand to hear him talk about his relationship with Melody, implying that he's still gushing about his relationship and how much sex he's getting to someone who's lonely and having trouble meeting women. With the guys snarking about him and the fact they stopped hanging out with him after one frustrated blow-up that was taken out of context, they don't come off looking much better than Jim.
It's not really helped by the fact that Jim's early characterization came off as genuinely nice and well-meaning, if unintentionally creepy in his over-earnestness. It honestly sometimes feels as though that was how Corsetto really intended him as first, then she realized that no girl wanting to romance him for no logical reason they could put their finger on, could superficially fit into the narrative of real Entitled to Have You so-called "Nice Guys", so she re-tooled him explicitly into one of them.
This was acknowledged by the author herself during the colored re-issues of the strips, in the comments she expressed that she wished she would have conveyed more clearly what was exactly what Jim was doing wrong.
Unintentionally Unsympathetic: Hazel; Corsetto has said that she deliberately writes her as a flawed character to make her more believable, however many times this crosses into Hazel being downright unlikable.
The Woobie: Thea is heading toward this territory. Loses her job: check. Sister has cancer: check. Girl she's taken with uses her for sex and exposes her to an STD: check. Yup, we've got ourselves a woobie.
She has a chalk board tally of girls she has turned straight.
Things are turning around, though — she had a Genki Girl almost literally fall into her lap and things have only been better from there.