honestly mate, normal padel evolution. happens to everyone.
few thoughts:
**don't fully ditch him, just diversify.** keep playing with him 1x a week or for casual fun games, but find 2-3 other partners at your level for the more serious stuff/competitions. nothing wrong with having different partners for different contexts.
**be honest if it comes up.** if he asks why you're playing more with others, just say you want to play with different people to improve faster. most reasonable people get this. way better than ghosting or making excuses.
**consider it might also be on you.** are you tilting visibly when he misses? body language and frustration from a partner is one of the biggest reasons people regress mid-match. sometimes the "weaker" partner only looks weak because the dynamic is off.
**how to find new partners:** open matches at your club, americano/mexicano nights, padel apps (playtomic, matchpoint etc depending on where you are in the uk). post your level honestly and play a bunch.
at 2.5 you're at the level where partner choice really starts to matter for progression. completely normal to want to mix it up. just don't be a dick about it and you'll be fine.