Many adults, especially young adults, begin a sexual relationship with someone without the benefit of a long-term commitment. Although most adults are more likely to use birth control consistently, even a perfect user can expect more than one unplanned pregnancies in her lifetime. And sexually active young adults are actually more likely to expereince an unplanned pregnancy than a sexually active teen. An unplanned pregnancy can put an enormous strain on a boyfriend-girlfriend relationship as each person is unsure of his or her responsibility to the other in the situation. Abortion is a common recourse in such a situation, and in fact women who live with a partner outside marriage are 3.5 4.0 times more likely to have an abortion than the general population.
Few relationships are able to survive an abortion.
Some women choose to continue the pregnancy, and in too many cases the man leaves her to care for the child alone. It's only at this point that she may realize that he really didn't love her but was only using her for sex. However, when sex is used to cement just any relationship, it can distort your judgement. Especially for women, having sex can intensify the feeling of being in love without actually deepening or solidifying the relationship. It can make either partner less able to look at the relationship objectively, making it more difficult to initiate a break-up even though it might be time, because you've invested something so precious.