IMHO, Ki has nothing to do with it; it happens in any student-teacher relationship; particularly female student, male teacher. (That's not sexist, believe me; it's just the difference in attitudes: when it comes to infatuation, romance-driven girls tend to fall in love; hormone-driven boys tend to fall in lust.) I've been on the recieving end of this situation twice; it's not a pleasant one for the teacher. You have to try to concentrate on teaching, but sooner or later, you'll have to deal with the situation.
Now, my case is different from yours, Janet, in that I only had to deal with teenage girls who at that particular time in their lives, tended to get their hearts broken about once a week. You, on the other hand, are ( I assume from your posts) a mature, intelligent woman who knows what she wants, desires...Yikes, I have no idea how I'd handle it.
My thoughts on it from the instructor's side are these: while it's flattering to be looked at in such a way (even taking into account that, by looking at me, they're showing uncommonly terrible taste in men
), a teacher cannot get involved with a student without both people losing credibility and risking serious repercussion. That's not always easy - a student with a crush can be a nightmare to deal with in class; concepts such as 'discretion' and 'subtlety' tend to go right out the window. Also, for fully mature students - say 25 and up, there may be a strong return of desire; a potentially fatal distraction for a teacher. Difficulties arise from outside as well: other students who see what's going on can blame one, the other or both; can see preferential treatment whether it exists or not. Same goes for the teacher's superiors. A student-teacher crush or affair is, to put it bluntly, one heck of a minefield for both parties.
All that being said, my own opinion on this situation is that it is not a high-school, military or federal class, it is a martial arts dojo; a social class populated by normal human beings. Both you and your sensei are rational adults, capable of dealing with the situation and making up your own minds without the impediments of doctrine or policy. Also, yours is, as you say, no simple crush, but love; that's a powerful and special thing. In the final count, however it works out, there's not a single damned person who has any right to tell you what you can and can't do, think or feel. My own advice would be worthless, but I would say choose caution; wait and watch and learn until you know without a shadow of a doubt what your feelings are. Then, do the hardest thing you possibly could; tell him. Talk to him about it; let him know how you feel; I think you owe that to both of you.
Hope it works out!