A new survey bySouthern Methodist University reveals that happy spouses tend to gain more weight than unhappy spouses. Researcher Andrea Meltzer says, ''On average, spouses who were more satisfied with their marriage were less likely to consider leaving their marriage, and they gained more weight over time. A happy marriage can lead to couples putting on weight. In contrast, couples who were less satisfied in their relationship tended to gain less weight over time. For four years, some 169 first-time newlyweds reported twice a year on their marital satisfaction and steps toward divorce. They also reported their height and weight, which was used to calculate their body mass indices. Spouses who were less happy in their marriage were more likely to consider leaving their partner, she said, and on average gained less weight over time. So these findings suggest that people perhaps are thinking about their weight in terms of appearance rather than health.