Terminating

I don't understand why people choose to terminate their marriage when at the same time, their children had grown up. Recently I get to know my childhood best friend's parents are about to terminate their 30 years marriage. Both her parents are so close to my parents that they used to own a company back in 10 years time. I would say my parents were lucky enough to build their own business and went through successfully after that. Yet, this man ( my best friend's father aka my dad's best friend) started to develop his business by borrowing capital from many people, including my dad. He didn't seem to tell his wife either because she didn't know anything till the day he was totally broke. His business was failed of course, due to some reason that I think it wouldn't be appropriate to tell here. Her wife was told by one of his husband's business partner recently. She was shocked, for giving his husband 200 thousand to support his business. But still his husband did not let her know that his business had closed down. My friend told me her mother was suffer from depression, and she can feel the melancholy. They(my friend and her mother) decided to shift to her home town, tried to avoid her husband and as well as the so called 'loan shark'. I did not know till i read those form my friend's blog. I tried to call them, my mom too. But they seemed didn't want us to interrupt. So, are they going to terminate their marriage which last for more than 30 years? Wouldn't it be so saddening? =(((