I am leaving

Don't you bother yourself with making excuse for people. If they don't come, then they simply don't. There will be no after thoughts of imagining the maybes. Maybe because this or that. If they want to be here, they will come, eventually. Or else, they will make an explanation to make you at least understand, because there is no too much of explaination for those who waits, it is only people who don't have the willingness to stay from the very first place. Action counts, but words are often reassurance that can clear all the grey worrisome mind. If they don't feel the need to give an excuse, then you don't have the responsibility to understand the ambiguity. You shouldn't feel guilty when leaving.