I don't understand this part of defying gravity

During defying gravity Glinda and Elphaba start singing together about defying gravity and how if they work in tandem they'll win, and then immediately after Glinda is like jk naaaw I'm not coming. This part really confuses me why she suddenly switched it up and then goes right back to her original sentiment. Can someone explain this to me, because it's very off putting when I watch it?

"Glinda, come with me Think of what we could do, together Unlimited Together, we're unlimited Together, we'll be the greatest team there's ever been Glinda, dreams the way we planned 'em If we work in tandem There's no fight we cannot win Just you and I, defying gravity With you and I defying gravity They'll never bring us down"