Yes, it is very much possible, I think, for an INFJ to be interested in someone without showing their interest and looking quite detached instead. What could break the ice is that you have to stop noticing her 'frozen' moments and just approach her, talk to her about something. Don't feel intimidated by her being that way, just ignore it. It is the outer shell that seems to be frozen, in her mind there are probably so many thoughts and her heart is overflowing with emotion. Try to notice the "real" her. That her who is very warm and feels so much without being able to fully express it. If she is an introvert, try to be more extroverted. If she will feel that you notice her fear or frozenness, she will become even more conscious of it. I don't know, I wish you all the best, however.