Ted listens, patiently awaiting whatever reveal is coming.

And then she stops talking, and Ted waits, expecting more, but she doesn't say anything more. Just that she had sex with some people, which seems.. underwhelming?

"...Okay?" he answers uncertainly, not sure what she expected his reaction to be. He pauses briefly, going over her phrasing in his wait. "Wait, are you saying you had sex with women, or...?"

Because that's the only remarkable thing he can think of regarding that, and she did just elaborate 'exercise partners' to mean women Sherlock had sex with. Which, obviously, would also be fine, if a little surprising.