I've already said that you might check Date A Live
: the 2009 ongoing 4-volume supernatural action romance light novel is focused on Sido Itsuka, a schoolboy who meet a girl who destroy everything. The only way to stop her is to date her. There's lot of action in it, and despite having post-apocalyptic moments at the beginning, there's no mecha (but the armored girls are still here) and the romance is often present. Also, the narration follows in the visual novel manner. Read the first chapter
to see if you might continue reading or not.