Megatron's response to that question is a sort of intensely weary grimace.

"I cannot imagine," he says, "being less jealous."

Unlike his confused response to Starscream's claims about his Megatron's relationship with Orion, this is nothing but the truth. The thought of how much more abjectly terrible everything between himself and Starscream might have been if it had started out as some kind of genuine romantic relationship honestly does not bear thinking about, and yet here he is, being forced to contemplate it.