I am a muslim, I dont celebrate Valentine's day. Because it is "human creation". Good muslim follows only Qur'an and Hadist, Sunnah Rasullullah (pbuh).

Valentine's day was based on Christian Catholic history long time back, to pay honour to one priest who married people in love which on those time was forbidden to get married coz ruled by the king. And he was killed coz of what he did.

So, it is NOT rooted from Islamic values. Yes, you are right, so many muslim also celebrated it, coz probably they are not good followers or they just dont know the story behind it.

Well, it's then back to everyone choice how to life their life. If you are muslim, and curious about this Valentine's day things, ask Islamic Scholar, then make your mind what you should do.

May Allah guide us on the right Path. Amieen.