If you're willing to drive 2.5 hours from Munich you can reach some of the famous ski resorts in Austria. A good starting point to find some resorts is this website, that maps a lot of them to a map. You're particularly interested in those on the left side of Austria. This site is very similar, but maybe even easier to understand, since here Munich is also displayed. Some of the biggest and most popular ski resorts in Austria are:
Ischgl (particularly to do some Après-Ski)
Kitzbühel (famous for its world cup ski race)
Lech am Arlberg (on the border between Vorarlberg and Tirol, it is immo the biggest ski resort around Munich)
St. Anton am Arlberg (its own ski resort, but also part of a association between various ski resorts in the Arlberg region. You can go skiing here and with the same ticket also in Lech and other resorts.)
Sölden (famous for the world cup start every winter and a lot of party going on there)
I tried almost all of them by myself, but I never checked if there is a romantic restaurant somewhere there. I would suggest you decide on a ski resort that suits you and then go to a website like Tripadvisor to see if there is a restaurant that is ok for you.