I haven't had a chance to read the whole thread, but I just want to put in a good word for ENTPs! When I was younger, I was hurt by a few of them, but I've learned that, at least for me, they are the people that I can have the deepest most passionate connection with (for whatever reason) and the feeling of balance is...extraordinary. There are down sides, of course, but I've come to be able to recognize ENTPs immediately and have made several of them, along with their INTP cousins, my very good friends.
I think the thing an INFJ needs to remember is that ENTPs are *very different* than you are. Their initial flightiness or unwillingness to commit does not mean they are not capable of very committed, passionate, loving relationships. The trick really is to not jump at initial signs of interest, even if you become lovers. When an ENTP is ready to commit to you trust me, he will let you know and never let go, but not a minute before.
I definitely think it's about maturity. As a mature INFJ, it's become much easier for me to give people the space to be who they are without feeling like I'm sacrificing or surrendering a part of myself in the process. When I was younger, I wore my heart on my sleeve for almost anyone and, naturally, got stomped on. A mature ENTP is more likely to have spent a lot of time chasing both women and his own projects and maybe even be searching for something more. He may be more ready to take and cherish what you have to give him.
That said, there is a lot about this that is individual. My sister, an INFJ, is dating an INTP. As far as I can see, they are seriously, deeply in love, but they have broken up and gotten back together *so many times* and well...there's nothing in her life that's not high drama. I've introduced her to MBTI and it seems to have helped them both a bit, but I think she just lives in an even higher key than I do (and I live in a higher key than most). I think she might be too easily hurt if she tried dating an ENTP.
But anyway, INFJs (especially the ladies), we need to be better at protecting our hearts and not giving them freely until someone has really built us a safe space for them in their own hearts. Just because we are so willing to give does not mean everyone is equally able to respect, understand, and protect the gift.
Long and short of it is I think I am going to keep loving ENTPs for the rest of my life. Hope I can marry one!