Heres the way i would approach it.
She knows how you feel,,so drop hints in the conversation that you're seeing other people. But, make sure you don't rub her face in it at all, and don't make it sound like you are serious about this other person.
She has gotten comfortable with you man,,you might as well have a dress on and be her girlfriend. (no offense implied at all) That might be how she sees you. Even if you aren't dating anyone, let her know you're hanging out with other girls. They might even be friends. Be a little mysterious. Just leave out details. Instead of saying, i'm meeting my ugly friend Emily at the coffee shop..... Say, you're meeting a girl for coffee after class to chat, we have great conversation. You get the idea.
I do this and it works. Women want to date the hot commodity wether they can admit that or not,,,plus even the most moral and good girls love a good chase. The good news is that even if she thinks of you as a friend,,she may still be possesive with you and your time. Bringing other girls into the picture will make her compete for your time. Thats a good thing.