Re: Dead end?
I agree, your teacher comes across as very sound, very similar to mine in fact, if my sensei comes and watches me do technique and chooses to move on without comment I take that as a compliment in itself. I've worked with other teachers who deliver differing levels of feedback from lots of positive encouragement on the mat to a small comment after training, I respect each for their own qualities and they all have their merits. It wouldn't surprise me if your teacher is much more aware of attendance and who is doing what than you are conscious of.
Our boys quit at 5th and 4th kyu because they got bored with repeating things they felt they already knew, all three having picked up the movements of basic techniques very quickly
All this says to me is that they weren't ready to carry on with their Aikido journey at that point and while I hope that they will want to continue it later because I'm sure they will get a lot from it if they do, if they choose to be active in other ways that's fine too.
Aikido is as much (maybe more) about training for your mind and personality as it is for your body and fitness, it sounds like you are learning and progressing on all fronts with your current teacher.