The line "We mustn't make love/have sex because I might accidentally/against my will hurt/kill you" sounds like "We mustn't have sex because I might get you pregnant", which is, it's true, becoming more and more disastrous an option rather than less of one in the overpopulated world.
And, seeing as even the pill, with "typical" use, is only 93%-95% effective over a year, and durex 84%, ( and I have checked both figures ), penetrative sex really is a huge risk to take in a society which seems to require most women to work, whether mothers or not, and bringing up a child costs so much money.
A man who says, "We mustn't do it" is going to seem very hot indeed.
It is that which makes him so irresistible to all the girls, ( not his so called prettiness etc ), because motherhood, even in the safest and solidest and most materially comfortable of marriages, is a kind of "little death" for many women now, especially those who are tasting the joys of independence for the first time.
And this may be what explains the runaway success of the film. It is speaking to and of the spirit of the times.
.