How about museums? Some areas have low cost or free museums, but you could always splurge a little. I'm not sure if museums ever do any sort of coupons on Groupon or anything like that...

Also, when it gets warmer, what about a picnic? You could find a fairly secluded spot where you don't have to worry about other people.

Walks or bike rides?

What if you combine two of your ides? Try bringing a board game to a coffee shop? Some coffee shops might even have games there like chess and checkers. You could bring a game that doesn't take too long, give it a whorl, and if either of you get too anxious, you can just leave.

You could also always dress up your stay at home dinner and movie night. Do something fancy, break out the nice dishes (if you don't have any, check out Savers or Goodwill for a couple of nice place settings -- all you need is two!), put on music and light candles. And then light candles while watching your movie. You could even do themed dinner and movie nights... Watch The Tiger and the Snow (and Italian film with the actor from Life is Beautiful in it), have Italian cuisine, and listen to Italian music during dinner. Little things like that can add variety to an otherwise in-a-rut feeling evening

Hope some of these help! Happy Valentine's Day!