Peach agrees to meet Bowser to actually negotiate a wedding.
Bowser shows up decked in his best wedding suit and vibrating from excitement but frowns and gets flustered at the sight of Mario and Luigi flanking Peach.
Peach : "The thing is, when I said before that I could not marry you, the issue was not only with you."
Luigi, between his teeth : "Yeesh, brutal."
Peach : "You see, despite my feelings for you, I can't just marry you because I wasn't alone when you proposed to me."
Bowser : *glares at Mario as he sees where this is going*
Peach : "So if you want to marry me, it can't only be me. You'll have to accept the-"
Bowser : "Fine, fine, I'll take the-"
"Three-"
"Two of you-WAIT what do you mean THREE ??!"
Peach and Mario point wordlessly at Luigi who does an awkward little wave. And despite the friendly smiles of the two others, Bowser gets suddenly hit by the awareness that if he says the wrong thing here and now, he won't have a shell tough enough to survive whatever happens in reaction.
So he accepts the offer. He feels like he's being scammed, because while he finally got Peach, he can tolerate Mario at best and what would he want with the Green Mario ?
Skipping to the wedding night (after the strangest wedding day ever witnessed in both Mushroom and Koopa Kingdom):
Bowser, laying on his bed, blushing, breathless and surrounded by three warm and sleepy humans : "Oh. Okay, I can get used to it after all."