@Tych Nah, I wasn't expecting him to ask something so reasonable either. He could just as easily say "I'm stronger than you so I do what I want" given the setting. But here he is, making an excuse that comes with excellent cover just to spend some time with her.
@Glomoro yeah but if he did that she would look for any excuse/way/method to get away from him and as for cover excuses that one is really good to against a doctor if you think about it in long term effects cause she is required to inform him if it reacts badly with other things