Dimitri could have all of Dedue's attention with only a word or a glance. Even if he opens his heart to others, that will likely never change-- Dimitri is important to him in a way that no one else could equal. Perhaps it's a product of their shared hardships, or perhaps Dedue would always have felt this way, even if they had met in less dire circumstances.

He laughs at Dedue's concern for fidelity, teasing him-- not unkindly, though. It is a topic that Dedue believes deserves due consideration, however, considering the nature of their situation.

"No, of course not," he says. "I was fully aware of your other lovers when our relationship began, and my feelings about it remain the same. But I did not have any other attachments, and thus it would not seem right for me to accept another's proposal, even if I did have an interest."

Dedue knew about all of Dimitri's paramours when this started, so there could be no infidelity. But Dedue had no paramours, so adding one in now, when that was not the situation that Dimitri had agreed to, feels wrong.

"I do not know much about how conventional relationships work, nevertheless ones that are more... complicated. I do not wish to cause harm to you or anyone else involved due to my carelessness or negligence."

There must be some way to include new people, he supposes, if Dimitri could start dating him without objection. Or had he been so readily accepted because the others had already been aware of their longstanding feelings for each other? He isn't sure, and it had never seemed like it would ever be a problem before this morning, anyway.