Sex has designed us, at least those of us who happen to be heterosexual, to procreate by making the so-called physical act of love as well as the mere thought of it pleasurable, at least to a great many people.
With contraception, practiced for millennia in different ways, couples have tried to gain the pleasure of sexual intercourse without the attending possibility of pregnancy and the responsibilities and risks that follow from pregnancy and having a child.
Yet contraception is not fail-safe, as I know two women who got pregnant despite being on the pill, condoms for their part can break or come loose as I myself have experienced and I also know a woman who got pregnant despite having an operation not to!
The surest way to avoid having children is of course to practice sexual abstinence but the power of Venus is such that even the most chaste man or woman may be tempted to give in to the temptation of sex if caught in the passionate heat of the moment.
Thus it would seem that nature cares not for personal preference and ideal conditions for having a child, merely the fact that we do self-perpetuate as a species, at least for as long as sex is practised by heterosexual couples.
Sex can be recreational, of that there is no doubt, but nature's agenda always lurks behind even the 'safest' sex that has ever been practiced.