You talk of a curious situation. If you had elaborated on how good she was in bed, perhaps the answers would have come in faster. Let’s suppose, she was indeed good in bed with you – one could assume that this said friend was in a similarly blissful situation. This would enhance your bonding with this said friend. You both know that he’s in a good place, and you both are happy for him.
If on the other hand, the woman was horrendous in bed, you’d have a deeper experience that ties you together. Far holier and insightful than most relationships are. While your penises won’t do the talking, you would be able to interpret every sigh of this friend. Your sense of empathy (I believe you may actually find one if this is the situation.) will grope towards the betterment of humanity in bed. Either way, your friendship with this person is now deeper, peniser and more straight than ever before.
As for being a conduit, I think she is more of an “enabler”. Now, we come to the question of nausea. I suggest you completely obscure the images of him being naked, and focus on the fact that it will be far more easy to spend time with her now. Make best use of her and it.
I suppose there is a reason why the word penis and pensive sound so similar.
PS – I wouldn’t know about etiquette, I live in a nallu-kattu house.