Very good point. Valentine's day is certainly not a frivolous holiday if we use it to celebrate God's love for us.
I want to push back on one point you said--that all other days are of commerce nothing more. 1 John 4:7-9 talks about how when we love others, we demonstrate God's love for us. In a real sense, we can and must celebrate God's love every day of the year by demonstrating that love in how we treat eachother.
that's right