Steve forces himself to focus, focus on shoving what he's feeling as far down and out of the way as he can before she steps into the hall, so when he turns around he looks as calm and collected as possible. Given the situation he thinks he's doing rather well.

"Sorry, I didn't want to intrude."

Peter steps out behind Olivia, both unwilling to leave her, period, and unwilling to leave her alone with a stranger. Even if it is a stranger she knows. He slips one hand into hers just so he can hang on to her and at least temper the feeling that she's going to disappear as soon as he looks away. "New friend?"