simpen
to fawn over someone who doesn't return the affection (a 'Simp' does this)
Origin
The 'simpen' derives from the 'Simp', which goes back to English 'simpleton' ('fool, dimwit') - Merriam-Webster dates 'simp' to 1903. In 1980s/90s US hip-hop and rap, the submissive 'Simp' stood in contrast to the dominant 'Pimp'. Around late 2019 the term exploded via TikTok as a meme ('Simp Nation'); to 'simp' means to shower someone with attention that isn't reciprocated. Its use is considered problematic and is often criticised as sexist.
Building blocks
Words in this expression
Examples
Er simpt für sie und liked jeden ihrer Posts.
He totally simps for her and likes every one of her posts.