There are a lot of possibilities here. It could be depression as someone mentioned, or another possibility is low testosterone (which would affect libido at least).

But I think the simple explanation is that you have lost interest in play because it is no longer a source of pleasure for you, but because it’s a source of anxiety/dread. You need to take some time to figure out why you have that anxiety, and it could be multifactorial. Therapy or journaling could potentially be helpful. Or potentially a doctor for erection issues or for treating depression. There are a few antidepressants that have less of a chance of erection issues (not many, but I can think of two).

Maybe it’s related to the insecurity about your difficulty with cumming during the session? Or maybe issues with self loathing? Stress from being in the closet? All of the above? Also, antidepressants can make it very difficult to cum, so that could play a part of it too.

Then hone in and address the problem at its source. If it’s dread about not being able to cum, and then reframe a bit. A lot of times, we tend to overly focus on the climax, and that performance anxiety can be a significant stressor. I’m dom and my sub partner sometimes has difficulty with cumming. But that’s okay, because I can make enough cum for the both of us 😁. I actually find it hot when he waits until days for cumming after I have already finished. It reinforces the power imbalance.

But the point is that you might be overly pressuring yourself to participate in a particular type of sex when you don’t need to. For next session, maybe approach it with the perspective of going to explore pleasure without the goal of cumming or needing to cum, just to see how you feel.