Do guys act differently around a girl they like?

Anonymous
I've a good guy friend and well.. though sociable and has a lot of friends, has a standoffish kind of vibe and is always in his own world, as such he doesn't observe people a lot. He has this tendency to go off alone as well and doesn't really tell you. However, he seems to act very differently around this particular girl..

She's very low-profile unlike him, but he always seems to notice her anywhere in a crowd. Like he'd just zero in on her, and he'd try to find ways to be physically near her though he's not the type to like to stand or sit near people, he likes his own space. I once saw him carry stuff for her, wordlessly. And he stares at her a whole lot but can't seem to do it face to face. So he sits behind her in class and looks at her or sneaks sideway glances.

He has been displaying such behavior around her since 2 years ago. Do guys behave like that around someone they really like?
Do guys act differently around a girl they like?
2 Opinion