There's a lot of single girls looking to have a Valentine and to celebrate the night. You don't need to buy her any gifts or give her any cards. Just take her out and enjoy the night like any other night. Don't put a big emphasis on it being Valentine's Day either. Just say let's go out that night. Then take her out.
Have a dinner, maybe see a movie, or do an action date, then get laid. That's all you really need to do, and since you've been dating for two months, it's appropriate to go out on a date. I've gone out with two girls that weren't my girlfriend's on V day and had sex with both of them. Girls get lonely on V Day and will have sex with you if you make it a good night. Don't force giving any gifts or making it out to be too much. That won't go over too well. People make too much out of Valentine's Day making you feel like you have to buy jewlery or expensive presents, it's just an observance. As long as you're spending it with a person you like, then that's all you really need to do.
Some of you say it's only for girlfriend's, that's not true, anybody can have a valentine and go out and have fun. Some of these sh1tty girlfriends that you write about don't even deserve a Valentine's day.