>>1246100OP here, I should have explained what I meant by similar. SukaSuka is post-apocalyptic yes but fantasy primarily, it isn't even set on Earth. And the focus is on the romance of two characters. Most high fantasy has the world on the brink of ending, or, like in Tolkien's universe as of the time of LOTR, it's just a few holdouts among the ruins of civilizations that experienced an apocalypse long ago, and most of the good things in the world have already been ruined. The mostly barren and empty world depicted in the LOTR movies has always given me a post-apocalyptic vibe.
But I digress. So just looking for a sweet fantasy/scifi romance, preferably with an age gap like in SukaSuka (big moe factor for me), with a man trying to protect a girl and make her happy, and falling (mutually) in love with her, and getting a happy ending with her regardless of whatever suffering gets in the way. Manga or VN works too.