Gaban and Sanji are different people, right, but there are some parallels (being #3, being a "missionary of love"). Gaban had had a lot of casual flings before settling with Ripley (remember he hit Shanks for mentioning it), but rn he doesn't seem to sleep around like Ray does as the latter has an open relationship with Shakky and they're both cool about it.
Sanji could've get laid with a hot mermaid way back on FI, he was simping a lot yet the ladies loved it anyways. His line for soba noodles in Wano was also like 90% ladies, so he might've had a chance there, too. But no, Sanji didn't have any one-night stands, so to me it seems like Oda is setting him up for a serious relationship. Or Oda just doesn't want to focus on such things for SHP.
Even if Sanji is married, I still expect him to continue being a flirt and a simp. If Pudding becomes his wife, her tsundere antics will make sense. That could be their running gag - Sanji giving compliments and having heart eyes about some chick and getting bonk'd by Pudding for such behaviour, followed by making out. Although we'd probably see it in the epilogue if anything.