Let me stop you right there and tell you why that's an awful idea.
What do you do when you've given someone a book typically?
- Expect them to read it.
- Expect them to enjoy it.
- Expect them to suddenly have better tastes in books than before.
- Want more recommendations from you.
Now, those things probably don't always happen and that's okay because by the time you see them again, hopefully they've figured out who to dance around the subject and lie to you. With your SO it was fine for Christmas because you aren't allowed to complain about gifts at Christmas, and for their birthday I imagine you had the tact to give something more traditional along with the book. But this is Valentines Day, the day of romance and passion.
You know what's not romantic? Realizing that somebody you love doesn't also love all of the things that you love.
So here's my solution to the dilemma:
Stick to the traditional stuff for Valentine's Day, chocolates and disgustingly cute and sweet cards. Save that heartbreak for some other time, like when you discover that they don't love your favorite band from the 90's or when you find out they think Julia Roberts is a talented actress. Until then, everything ought to be sunshine and rainbows.
(As an aside, if you ever search google for "true .gif" you should prepare for the torrent of Doctor Who and True Blood fandom that Tumblr is about to unleash on you. Just thought you should know)