So many different things being discussed here.
Isn't it normal for the honeymoon period in a relationship to expire, between any two people and for things to seem more normal? This doesn't seem to be type dependent.
ENFPs do idealize their mates but this is who we are and believe me, it's not just mates we idealize. Friends, family, all of the people we care about are given similar treatment, at least in my life. It doesn't mean that we're constantly abandoning people and running off to find new friends/family/mates...
The OP's sentiment is shared by many of us when we come face to face with the undeniable reality of someone in our life that we may not want to face. The key is accepting that (the negative aspects) as part of the picture and still being able to see the positives, what they bring to our lives. People aren't black and white, after all, in spite of our best intentions to paint them that way!
There's a difference, I'd like to think, between reconciling the idealized image of a person and the reality of who they are - complete with flaws and frailties and moving off to greener pastures at short notice. The latter is more an indicator of commitment issues which are certainly not the forte of any one type.
Syptg, I get what you are saying with suggesting that ENFPs get a better sense of what they want before jumping in headfirst and then panicking. At the same time, an extreme form of this is also a form of idealization. The idealization here is of the perfect mate, someone who can barely exist in human form. There must be a happy balance, excuse me as I trip over my own ENFPness. We could eliminate less compatible potentials initially on the basis of some must-haves or must-not-haves but after that, it takes time and inclination at both ends to really explore the fate of the relationship. This process could lead to deeper forms of commitment. It's hard to know whether someone meets everything you need and you meet their needs without this process of exploration.