Bohemians of times past

By February, Michelle realized she was pregnant.  With Sartre, as with Boris, she became pregnant the very first time she slept with him.  Sartre could not believe it at first.  He had practiced his usual method of contraception, coitus interruptus, and thought it foolproof.  "Of course, it wasn't safe at all," says Michelle Vian.  "Sartre would withdraw, and ten minutes later, he would make love again.  We [TC: who?] didn't know it back then, but it takes only a drop of semen..."

Were any of these sex lives any good?  And does this help explain Sartre's blindness toward Stalin?  Was he simply pigheaded when it came to his perceived self-interest?

The quotation is from Hazel Rowley's excellent Tete-a-Tete: Simone de Beauvoir and Jean-Paul Sartre.