Amoebas at the Pearly Gates

Dorothy wants it all to end. Years ago, she made Guy promise to end it for her if her health and pain ever got to this point. Torn by love and duty for the love of his life, he cannot bring himself to do the deed. So, he decides to go out with her and fabricates a fatal diagnosis of his own. She reluctantly agrees to a dual suicide, always poking him with her acerbic wit. But Guy's no good at this sort of thing and their attempts go comically awry, only attracting the suspicion of family and neighbors.
Ultimately, Guy and Dorothy fly away in a small plane, intent on a quick and splendid splashdown into the ocean, but that's when it all hits the fan.