This is one part of a larger role. The couple is very close and isn't afraid to show it. Not like THAT, but playful sweet talk in an E-rated way. Later, he's forced to watch his girlfriend's face get taken away! Both he and the female role in this two-part character, contrary to almost everyone else, is ENTIRELY comedic effect. I'd recommend piling it on, making almost every line in that lovey-dovey tone. And even the ones that aren't like that, try to make it sound like he could slip back into that voice at any time. (Just a heads up, this role can have a strange line or two. I hope you're okay with that...)