Rito keeps trying to confess to the girl he actually likes, but he's engaged to an alien princess, and the show finds comedy in that specific misery every single episode. The fanservice isn't window dressing, it's the actual plot engine, the thing that keeps throwing obstacles between him and what he wants. Nothing here pretends to be deep, which is why it works: you watch a guy get increasingly tangled in romantic chaos and laugh at how thoroughly the universe is conspiring against him.
Rito Yuuki has never caught a break with romance. Every confession crumbles, every attempt at love falls flat, and he's resigned himself to another night of solitary misery in the bathtub. That changes when Lala, a alien princess with a tail and absolutely zero concept of human modesty, crashes through a dimensional portal and lands right on top of him. She's fleeing an arranged marriage on her home planet, but the universe has a cruel sense of humor: in the chaos of their first meeting, Rito accidentally triggers an engagement ceremony that binds him to her instead. Now he's stuck with an extraterrestrial fiancée, her alien entourage starts showing up on Earth, and his chances at a normal life evaporate completely. What follows is a collision of romantic comedy and science fiction absurdity where Rito juggles his original crush, his new alien girlfriend, and the growing cast of space visitors who seem determined to either kill him or fall in love with him. The show leans hard into slapstick chaos and comedy, with Rito's bad luck becoming a cosmic force of nature.