Considering Shin isn't Makoto, yeah. Aiko treats him (or has treated him up until the end of ep. 5) like a brother, on top of that she's going out with his best friend. Normal guys aren't going to fuck with that, that's clearly drama territory.
Noe is ultra-cute to the audience, but she's still seems pretty weird to a normal guy like Shin, even if he's warming up to her.
Hiromi is your standard average female that says one thing but means another and gets pissed that you can't infer the complete opposite of what she says. As fas as Shin knows, she likes another guy, and he wants her to be happy even if it's not with him. He also knows his mom is a bitch and doesn't want to stir that pot of drama either.
Spineless? Nah. I can feel for the guy.