INFPs can be
very flirtatious! The shy sensitive side is just one facet of the personality -- they can also be social butterflies and shameless flirts who are the life of the party
That flirtatious, social side is what I like to think of as the INFP's inner ENFP coming out to play when they're very comfortable and around people that they know well.
I was out last night with some friends, including an INFP and her ENTP boyfriend. She's a beautiful girl and she attracts a lot of male attention, and she was definitely channeling her ENFP self last night because she did flirt with some of the guys at the bar, not excessively so, but she was having a good time and letting loose. Her boyfriend was not happy about that! Being familiar with personality type, I tried to tell him not to take it personally, that she's just a free spirit and doesn't mean anything by the flirtation. Not much solace to him, and I can certainly understand his side too, but anyway, that just goes to show that flirtatious INFPs do exist.
Another male INFP that I know well was a HUGE flirt in his younger days. He was quite the Romeo and bedded a LOT of women and was pretty much allergic to serious relationships.
Both of these individuals are definitely INFPs rather than ENFPs because I've typed both of them, and they both are very quiet in most situations and highly value their alone time. But it's kinda like when I'm very comfortable in a social setting I let out my inner ENFJ -- they let out their flirty ENFP selves
