Euthanasia for psychiatric conditions is currently legal in Belgium and the Netherlands. It is also highly controversial, as illustrated by some recent, high-profile cases. In this paper, I show how a better understanding of the associated phenomenology can inform debate in this area. I focus on how phenomenological changes that occur in psychiatric illness can erode the ability to experience and entertain certain types of possibility, making some scenarios seem inevitable and others impossible. Although strong convictions that originate in competent decisions differ from verbal and non-verbal behaviors stemming from losses of possibility, detecting the difference is by no means straightforward. I add that a sense of the possible can be sustained, enhanced, or diminished by ways of experiencing and relating to other people. Consequently, the extent to which decision-making capacity is impaired in a given case may vary with interpersonal context. I consider the implications of these points for evaluating euthanasia as a response to mental suffering.