Actually I tend to stop gaming on the run up to valentines day just to avoid this problem, but I would recommend just inviting her to hang out at yours on saturday without mentioning the fact that it was valentines day, and then on the day act surprised when you find out that it's valentine's day.
That or just mention how you hate valentine's day as it's an obligatory day for saying you love someone and you think that while the sentiment of the day in question is a good one, the fact that you are obligated to do something on that day bothers you and you much prefer to declare, celebrate or otherwise enjoy your love in a more spontaneous and therefore special manner, savvy?
And, dude, the use of 'mounting' just sounds so vulgar, unless you're actually planning on mounting her on your wall as some sort of trophy, anyway. Sorry, personal gripe.
