How can I help my parents with their marital issues?

My parents have been driving cars for local dealerships for about three years. Nine months ago they took a new job and are now having marital problems. My mother is very old school and thinks that men and women should not drive together unless married (or unless she approves of the women, she is very jealous). She has told the woman who does the scheduling not to send my father with a certain lady who is very flirtatious. I think that this woman finds it amusing that this upsets my mother, but she has lost twenty pounds and just told me that she has thought about suicide. I told her to quit but she said they need the money too much. I told her no amount of money was worth the happiness of a good marriage and the talk of suicide. Please help, my poor dad is in the dog house most of the time and to my knowledge has not given my mom any reason to not trust him.