Well, depends on how you define obsessive. If you mean constantly thinking about them .. daydreaming about doing things together, etc .. I think that's called falling for them.
Maybe it's something more .. like if it's someone you don't see as much as you'd like and you find yourself, I don't know .. trying to hold on so tight to every moment .. because you don't know how long it will last or how much time may pass before seeing each other again .. mmmm, maybe that could be considered obsessive. Don't know sure .. but, I fit into both of those. I hear ya.
Getting a job would help somewhat I guess .. having things to do that make you happy apart from your, "interest" certainly would crank it down a couple notches as you have other things to occupy your mind. But I know how it is though .. to become so fixated on someone sometimes. Wish I had a solid answer for you but unfortunately, I'm kinda searching for it myself. The human mind is incredible but .. it doesn't come with instructions.
And the heart .. who can understand that even WITH instructions?