It's very easy for Levi to redirect Erwin's attention back to him. This isn't really something Erwin cares to dwell on; his dick wasn't working, and now it is again, and he sees no reason to delve into all the possible reasons for its few months extended leave. He knows, on some level, that this is connected to all the other stressors in his life, but he'd rather not poke that nest of snakes. Things are going well enough here; there's no need to disturb the peace.

He comes out of his own thoughts quickly enough when Levi offers to help, then admits his own inexperience. It's something Erwin has suspected for a long time, but never had any reason to question or investigate further. Most people in the Survey Corps had assumed Levi simply wasn't interested in sex, Erwin included; even here, in this world, he's thought Levi was content with kissing and the closeness they have and didn't need anything else. Him offering to help is both exciting and a little worrying.

"I don't want you doing anything you don't want to do." Erwin catches that blush, though, even with how close their faces are, and he dips his head to kiss along Levi's neck again. That, he knows Levi likes. "I can take care of it myself if it's not something you're interested in."