the whole lock-mode and fickle (in love) thing is def a sign of a young INFJ. I can certainly say I was that way. blame it on an over-developed Fe and underdeveloped Ti. Ti usually kicks in around our 20's and leads to A LOT of growth. prior to then, we can be highly judgemental, definite know-it-all's, inflexible when it comes to our beliefs, and in my case...immature when it comes to love, or better stated...immature when it comes to selecting the right partner. Many times it resulted in falling in love too quickly, or falling out of love too quickly, usually as a result of realizing, I fell too quickly into a relationship. After the initial "fun" stage sets in, many times I would realize how un-suited my partner and I was for each other. I actually didn't grow out of that until my 30's. I blame it on INFJ idealism...then of course we mature and Ti kick in and gives INFJ idealism a real good kick in the nuts. *sigh*
Anyway, once Ti kicks in, INFJ's have the ability to become extremely open-minded individuals, almost on par with INTP's I think. I've read ppl mention how INFJ's can sound almost like INTP's when explaining certain things. I definitely agree with those statements and thank Ti for that. It makes me question the validity of my feeling's, and acts as a counter-balance to my Fe. It helps give way to reason and logical ways of thinking. Of course, Fe usually wins out in the end, but I can't even begin to describe, the intense internal battle that occurs between Fe and Ti. It's almost like an angel and devil speaking to me and they are usually in full on debate mode.
I'm learning to quiet the Fe in certain situations. Situations when emotions should not be a factor in making a decision. I usually run to my INTP bf for help in that area. It's still a work in process I have to admit. Damn Fe! *shakes fist* LOL.