Don't believe me? Listen to St. Louis Symphony Orchestra music director David Robertson's take on the pieces, which he selected, in an audio clip here. The guy understands them way better than I do and describes the underlying themes and contexts.
From a civilian's point of view, the two pieces are engaging, tense, at times melodic and not at all "difficult" in the way some modern quartet music is. Yes, both address themes of war (perfect for Valentine's Day!), and hit darkness during the compositions. But they're also wonderfully accessible.
If nothing else, it's a chance to sit in the city's most beautiful building with the lights down low and see the reflecting pool as it shimmers. You won't regret it -- and your date will be very impressed with your cultured tastes.