the same applies here, that guy believes he has nothing of value so why would girls be interested in him?
Well, most harem dudes I've seen really don't have anything of value to them. Only exceptions that come immediately to mind are Tenchi who's genuinely nice and does become more than that, and Negima, who's pretty damn impressive even from the start. But then, both stray into adventure rather than remaining pure harem.
It's funny that a lot of artist in general have issues drawing believable boy/men. You'd think because they are flat as board and have no curves it would make everything easy starting with clothing, but it almost feels like it's so simple that it becomes hard. Y'know what I mean?
It takes a pretty in-depth knowledge of anatomy to really pull off a variety of types. It's a bit easier in cartooning when you can work with simple shapes more, but with realistic figures you have to work a bit more. I can't remember who said it (Mike Matessi, maybe?), but the idea is you draw a generic head or arm or torso or whatever over and over again until you've mastered it, and that knowledge allows you to then draw specific heads at will.
To be honest, a lot of fanartists don't really go through that repetitive training stage. Which isn't necessarily bad since fanart is about enjoying and sharing the love, rather than being a detailed illustrator. However, it does get difficult to work outside your comfort zone, whether that's focusing on males or females, beefy types or waifs.