God gave marriage to us, and He doesn't ask us to love our spouse only when it's convenient or easy not at all. Marriage in God's eyes means not just enjoying each other's company, but helping each other when life turns hard.
In fact, one reason God gave marriage to us was to help us through life's rough places. Life isn't always easy or enjoyable; in fact, life is often hard and difficult to bear alone. The Bible tells us that when God created Adam, "The Lord God said, 'It is not good for the man to be alone. I will make a helper suitable for him'" (Genesis 2:18). That "helper" was Eve, and since that time God's plan is for a husband and wife to help and encourage each other, both in sickness and in health.
I'm sorry for your friend's selfish decision to abandon his wife during her time of need. And someday he may live to regret it, because he may find his next spouse will treat him the same way he has treated this one. The Bible warns, "You may be sure that your sin will find you out" (Numbers 32:23).
Pray for your friend, and ask God to help you confront him with the selfishness of his ways. In addition, make Christ and His love the center of your own life and marriage. Many people today take their marriage vows lightly but God doesn't, and the reason is because He loves us and knows what is best for us.