Sanji was surprised to learn that Pudding was the reason his friends had gotten this far. That they had planned to meet on the coast, with him in tow, so the Straw Hats could all make a quick escape. While he appreciated it, he wouldn't have gone because he was trapped, in more ways than one.
"My family sees me as a failure and can't stand my existence. Eira was the only one who truly cared for me and showed it. She's the main reason I was able to set out to sea. But if I resist this marriage, everyone I care about will die, including my father figure in the East Blue. There's no way out of this."
And so, with an ache in his heart, he accepts the marriage with a condition.
"If I accept this, I want Big Mom to let my friends go. They're going after Luffy and the others."
Pudding tries to apologize for her mother's actions but Sanji reassures her that it's not her fault. "I'm happy to have escaped for as long as 13 years. I met kind people, those I consider family and friends. I'm indebted to them all. I don't want anyone to get hurt, so my adventure ends here."
"Sanji-san!" Pudding sobs. "I won't let your marriage with me be hell! ...Oh, I'm sorry! You're suffering. Why did I say that while you're in pain?"
The blonde, ever so respectful to women, is thankful for her words and begins to hope that this marriage truly won't be terrible. His mind flashes memories of his friends while he approaches Pudding, who's panicking at having potentially offended him. He pulls her into a hug, effectively cutting off any further hysteria.
"You're my salvation. If I'm good enough for you, let's get married tomorrow."
Though, he wished that the one in his arms, the one he was speaking to was the girl he'd always see as his light in the darkness.