The Roger Pirates' romantic pairings are surprisingly sparse in canon, which makes fan speculation run wilder than a knock-up stream. Gol D. Roger and Portgas D. Rouge is the ultimate tragic canon couple, and that sealed-backstory feel might explain why fans rarely try to matchmake the Captain with, say, Shakky.
Where the real shipping frenzy happens is with the younger generation, the apprentices. Buggy and Shanks is a colossal one. Their chaotic dynamic as kids, the bitter-sweet parting, and the decades of parallel lives they've led fuel endless 'what if' scenarios. It's a classic opposites-attract, friends-to-rivals-to-? ship with a built-in fifty-year time skip for angst. For Crocus, honestly, I see more jokes about him and Laboon than any human pairing. Silvers Rayleigh and Shakky are already a married, retired power couple in Sabaody—they're so perfectly established that fans just bask in their vibe rather than ship them elsewhere.
Then there's the deep-cut one I stumbled into on Tumblr: Scopper Gaban and that unnamed female crew member from the Oden flashback. There's barely any material, just a few panels of them standing near each other, but the fandom latched onto the idea of a quiet, competent duo holding down the ship's logistics. It says a lot about how fans will build entire worlds from the barest glimpse.