My headcanon is that after he accidentally got knocked up, he just sorta figured there was nothing he could do to avoid accidentally having sex, so what's the harm in doing it intentionally? At least that way it's easier to recognise all aspects as consensual.

Anything by Dr Karl Kruszelnicki. He's an Australian science communicator who as far as I've seen is the gold standard for bringing science to the masses. As he says "It's not the answer that gets you the Nobel Prize, it's the question!". He also won the 2002 Interdisciplinary Research Ig nobel prize for his comprehensive survey into belly button fluff.