I think also INFPs are the type most inclined to be unsure. I know some ISFPs , they sometimes also have problems with there confidence, but not as much as INFPs often have, because there provides them with a much better connection to the 'real' world.
For me I can say I know this Situation from my youth when a girl is flirting with me and about a week later I start thinking "Hey, has this girl really flirted with ME?? Am I REALLY sure she meant ME? Damn!"
Today this realization goes much faster but can also take up to an hour or longer. And I also like it when girls start the Interaction with me. Its nothing more than a clichee that the man should start everything, Ihope for all INFP guys this is going to break up in the future :wink: