Seams good, the heroine is cute their relationship is interesting but i don't think it can end well with the underlying premise, i bet i will end with either she confessing or he confessing without wining witch would be a crap ending.
A hostile alien army came charging through a hole in space — we're standing 300 feet below it. We're the Avengers. We can bust arms dealers all the livelong day, but that up there? That's the endgame. How were you guys planning on beating that?