I keep finding my self faking romantic feelings and love.
What makes you think you're faking love and romantic feelings?
I tell my girlfriend I love her genuinely, but I don't truly love her
You shouldn't fake how you feel about others and mislead them. If you don't have those feelings yet, you should be mature and communicate that to your girlfriend. If you don't you will regret not being genuine in the future.
Nonsense. I love to watch people have a reaction.
Lying to your girlfriend can really hurt her if one day you brake up and say in anger you never loved her anyways. You should be able to be authentic.