Hoshi no Koe, Iriya no Sora, UFO no Natsu Recommendations
In both animes there is a girl who's fighting against aliens to save the Earth. In both animes it get's really dramatic and there's a romance thing going on to. Both are very sad.
If one got you you'd definitely like the other one too.
The main female is fighting against aliens who are attacking earth and they both have a guy they like very much and that they want to protect at all costs.
The setting and the atmosphere are quite similar. Both anime are really touching and leave strong feeling of melancholy in the end. Also, they both have great soundtracks, that perfectly matches their mood.
Similar story - girls gets to fly a spaceshuttle, boy stays on earth.