You return to the living room and sit down, perhaps in the hope that you can pretend you really didn't just walk in on Sarah and see her wearing a diaper.
After a very long few minutes Tanya enters the living room. "Sarah's upset. I don't think she wants to go out with you tonight."
"I'm really sorry." you say. "I shouldn't have let myself into her room like that."
"No." she agrees. "You shouldn't have."
"Can I go talk to her?" you ask. "I feel really bad about this."
"I don't know." she replies. "She's really embarrassed that you saw her diaper."
"Why was she wearing a diaper anyway?" you ask.
"She always wears diapers." Tanya says. "She's completely incontinent."
"Oh." you say. That explains why she never let you touch her down there. "That's awful."
"I guess you won't want to go out with her anymore." Tanya says. "Now that you know her secret."
"What sort of person do you think I am." you respond defensively. "Of course I still want to go out with her. There must be something I can to to make this better."
"Maybe she wouldn't be so embarrassed about you knowing she wears diapers if you wore them too." Tanya suggests.