In stereotypes, it's usually the girl who asks the guy "Does this dress make me look fat?" and it's a question that's hard to answer because you can insult the girl from your responses alone Now it's Jake asking the question.
They probably will, but first thing's first, Finn actually has to talk to FP after not seeing her for so long. Rather than trying to pull some big heroics only to ultimately fail miserably like he did in "Red Throne", he should start small and help Phoebe with the smaller tasks in the Flame Kingdom such as helping with some of the requests that the regular citizens have daily. Through the tasks, he can learn more about FP through her citizens beyond the regular couples stuff they were doing before, and as he continues to help regularly with these tasks, Finn will begin to have more respect for Phoebe, her role as the neo-Flame King, and the things she values such as her honesty policy and her scented candles.