Speaking as someone who has battled both primary and secondary infertility, it is NOT the responsibility of young women like yourself to solve the problem of older infertile people, and no one should ever make you feel morally obligated to do so in any way.
Although the guy involved can have his opinion, the plain fact is that his health and life will never be put in jeopardy from pregnancy (planned or unplanned), so the final decision lies with you. If you are 18 or older, you can obtain an abortion on your own, no parental notification or involvement. If you are under 18, then it will depend on your state's laws. If you're under 9 weeks you can still get a "medical" abortion, which involves taking medications that block production of progesterone, thus triggering a miscarriage. You still need to be seen by a doctor and there is a small risk of serious complications, but medical abortions are generally quite safe (and have NO negative impact on future fertility). If you're too far along and/or the abortion is incomplete, surgical abortion is the next option. Vacuum aspiration is the most common method in early pregnancy, but D&C may be necessary.