This sounds selfish to some, and realistic to others. So many comments here are inspiringly thorough and carefully analytic, but I don't think we can fully converge until we see that the tension between individual differences and norms intended to support relationships is inescapably a source of variable solutions. So live and let live. Ask, but accept rejection.

Some of us would like others to be guided more by adherence to principles, for example, than gut feelings in the moment. This enables the argument that penises shouldn't matter. Or we are carrying fears taught us by our parents or friends that form part of our worldview, and often we have not fully considered their validity. Or we feel some mix of gender characters that doesn't have a name. and we are trying to fit into currently accepted boxes so that someone will accept and love us. Or, .... a lot of things.

We all want to have the largest circle of acceptance and romantic possibilities. Being trans means we are a minority in a minority, which brings both additional minority stress and the simple fact of being of attractive interest to a tiny fragment of the population. So, we are more desperate sometimes. Marla felt encouraged by your friendship and acceptance and wanted more. You clarified that you already knew yourself well, and the deal breaker was the penis, not the transness. You were able to get by the moment.

But the moment stuck, and you wanted to write about it. It could be that there was something else that still needs to be discovered.