It means that the person you are referring to is in love with hentai.
It was originated in some discord server called meme harem where the user described hentai as an art form that is formed with love by jacking off some 2D Characters.
Bob: Wow. Richard is in HentyLovey all of a sudden.
Billy: Sure does, he watched 4 episodes of Gakuen De Jikan Yo Tomare. 8 times. Back to Back.
Bob: Impressive. What a strong hand he got there.
The study of hentai and affiliated aspects of lewd Japanese animation and art. Can be studied and examined at levels up to university, and is a well respected and practiced field of animation examination.
something or someone who is simply amazing that you can't find the words to describe. The description adds to every positive, uplifting word found in the dictionary.