AIstroStrengths
Libra (earth) and Capricorn (air) see the world differently — one through practice, the other through ideas — and that can be enriching: diplomacy, a sense of beauty gives discipline, ambition ground to stand on, discipline, ambition gives diplomacy, a sense of beauty a fresh perspective.
What to watch for
Earth can find air inconsistent, and air can find earth too literal. If you're both willing to explain your reasoning instead of assuming it's obvious, understanding comes quickly.
Pair dynamic
You're both natural initiators — decide who leads and when, so you're not both reaching for the wheel at once.
Sun-sign compatibility is a general picture based on elements and modalities, not a precise forecast for specific people. Real relationships depend on far more than a birth date.