Ok, let me explain something about Bowser × Peach - Mario
Bowser and Peach are GODS.
Peach is WAY higher ranked than Bowser.
Mario and Luigi are two dumbass Italian plumbers that got themselves stuck in an alternate reality where they became what amounts to shrine maidens for the local over deity enacting a very hazardous ritual play to keep her four spirit energies in balance in exchange for Quasi-immortality.
Bowser can come back from the dead, he's a dragon turtle Kame, and he only kidnaps Peach because if he doesn't she'll kick his
ass. The one time he breaks script and kidnaps Mario and Luigi instead she
wrecks him with BS Over-Kame magic, and he's NEVER TRIED THAT AGAIN!
Daisy, by contrast, is a sorceress queen, and she's cool and all, but there's a reason that she and Luigi are an item instead of Peach's main man Mario 'Jump-Man' Mario: to whit, Peach would shank a bitch. (Or maybe just trash her with divine power, doesn't make much difference.)
Bowser raping Peach? OMG, that's so stupid it's funny! Peach
likes getting kidnapped and rescued, but he steps one
toe out of line and he's gonna get "Hadoken!"-ed into a
world of pain!
For a more through and detailed explanation see this video: