I remember that I used to get REALLY annoyed by ukes who were not 'behaving properly.' I also remember that there have been nages who have gotten REALLY annoyed at me. Nowadays, it can still happen that I get pretty annoyed, but things have changed a little bit. I think I've gotten a lot of mileage out of the idea that the uke is always doing ukemi to the best of his/her knowledge and ability. Ultimately, if it is not what I want, I have three options. The first (the option of humility) is to explain that I'm having trouble and ask for particular kind of ukemi. The second (the option of generosity) is to try to teach the other student in hopes of showing them a path to greater knowledge or ability. The third (the option of aiki?) is to simply work with whatever I've gotten to the best of my ability.
The third option is 'best' in some ways because it always 'works.' I simply do the best nage I know how and uke does the best uke they know how and, by definition almost, we are doing aikido. My technique may not work at all, but ultimately there is nothing wrong with that. It will always be an opportunity to notice what I still have to learn.
This is not to say that I do not opt for options 1 and 2 sometimes. There is much to say for and against them, but there is no reason to cross them off the list.