I personally can’t even fathom going on a TV show to find love lol, so you’re not alone in this thinking but it really is the premise of the show, so I don’t blame her for trying to find a stable relationship on LI. About her and Callum being weird together; I guess they were but I never thought they were awful together.
https://www.reddit.com/r/LoveIslandTV/comments/g1l9de/shaughna_and_callum/

