If you put a thread in the middle of a kiss, you’re going to entangle it. Things can get pretty messy in a kiss, so adding a thread to the mix will definitely entangle it.
This is your first kiss ever so getting a thread to entangle between your lips was really bad luck (らく). The person you were trying to kiss got really grossed out by the thread and tried to push you away but was so entangled with the thread that they were unable. Bad luck indeed.
Currently there are no similar looking kanji which exist in the WaniKani learning system