First, nothing says the other person is less important to you than a text message! Put away your stupid cellphone and get out of the pen.
Second, a handwritten letter can be quite romantic and allows you to say what you really want to say in style. If your friend has a sense of style, she will appreciate it.
Third, the box of chocolates that usually accompany this note is usually very welcome by females, for some reason (apparently there is a tie to the pleasure center of the brain when they even see chocolate).
Last, if she is getting texts all day, you will definitely stand out as one of the more sincere candidates if you have given her something that persists beyond the battery, and that must be literally discarded to be forgotten.
Put down the cell, and pick up the pen. That is my vote.
She’s available and you’re available, romantically?
Then sure! It’s a perfect excuse to let her know!
If you want to go with something simple (low risk of rejection, a high risk she might miss your point), I’d say, “Happy Valentine’s Day!” and see if she responds by upping the romance or keeping things platonic.
A bit more romantic (read: more likely to get your point across) would be, “Happy Valentine’s Day, [her name]!”
If you want to be really, really clear (which means you don’t have to wonder whether she turned you down or just missed your intention), I’d say, “Happy Valentine’s Day, [her name]! Will you be my Valentine?”
Valentine’s Day is great because I feel like when you confess to your crush on that day, it’s almost expected. She’s probably already wondering if she’ll get a text like that, even if she isn’t yet thinking it might be from you!
To me, that expectation actually lowers the pressure on her AND lowers the risk that she’ll feel caught off-guard or awkward, which means it’ll be smoother whether she accepts you or rejects your advance. I think it’s way more vague to say “Will you be my Valentine?” than to ask her on a date – which is great for you because the less unnerved she is, the more likely you’ll get a positive or at least neutral response.
Go for it!