My first thought was it sounded a bit Fi polr for her to say that outright unless he did bring up sex at some point before? Then he mentioned she said she would go for his son if he was older which also sounded like F is not her strength. Not specifically Fi polr even if my first thought. Like who says that to a guy they are dating, even if you are thinking it? I am a bit at a loss too. Maybe an E7 or EP is more likely to blurt that out. Idk. :/
I am only basing this on the few ESI I know well. Just doesn't seem their style but they do not represent all ESI.