He may be cheating, but chicks should always keep that thought in mind with guys anyway. He may be under stress too. Stress and other factors can cause a reduced sex drive. Not only that, but sex with the same chick gets boring after a while. That's why marriage life tends to get boring.
International relations, public affairs, and international law. These degrees may help you get a job traveling to fascinating places for companies or for the government as a diplomat.