I'm thinking of spying on a girl.
Why would you want to spy on a girl for?
I want to know if she has a boyfriend.
By spying on her you're invading her privacy. It's stalking and it's wrong. It's not your business to know if she has a bf or not.
But I think I love her and I dont want to lose her. I want to be with her forever. I want to know if my love is real and if she's the real deal.
Spying on a girl is not something that is going to bring you closer to them. If you want to know if she has a boyfriend you should just ask her. If she caught you trying to spy than I would assume she would not want to date you.