My sister is 45 and having an affair with an old boyfriend from her youth. She says she loves him, he loves her, and they wish to pursue a life together. They are both married, though he is separated. My sister has a wonderful husband who is devoted to her even after discovering the affair.

Our families are close, and we are in shock at this heartbreaking news. I believe my sister is going through a midlife crisis. Her husband is still willing to save the marriage, but he is tired of her obsession with this other man.

My sister has three children, the youngest in his late teens. She quit college when she discovered she was pregnant and got married at age 20. Her husband finished his education, while my sister worked to support them. They were on the verge of financial security when she met up with her old boyfriend.

One thing led to another. Now she and her husband will probably divorce. When all this started, she saw a counselor. She said the counselor commented her affair sounded like "a love story." I'm sure my sister told this professional only what she wanted and left out how she and her husband raised three wonderful children.

Our whole family is distraught. We cannot figure out what went wrong. I am angry. We love our brother-in-law so much and are concerned about him and the children. She says they are doing fine and will get over it in a few years.

My sister mentioned recently she "had to get married." I believe she is using that as a tool to rationalize what she has done. I feel I am standing back and watching her make the worst mistake of her life. How do I persuade my sister to seek professional help to guide her through this life-changing decision? -Jocelyn