Questions: Relationships

At what point should couples bring others in to help resolve problems? Whether that help be friends, family, marriage counselors, etc.

I've read this infidelity story before. I'll refer the names as Jane and Tom.

Jane was 19 and Tom was 20 at the time. They've been dating for 8 months or so when she got caught cheating. She cheated with Tom's good friend. Both got caught falling alseep in Tom's house, on his couch in a compromised position with the TV still running, an empty bottle of rum and empty snack bags. They had already finished the deed when Tom arrived. His friend was only in boxers and she dressed up with jeans but only had bra. Alcohol was involved and the cheating went on for nearly 3 months.

Tom somehow forgives that, reconciles and still marries her 5 years later. Jane changed for the better though, by her own admission never cheated again. Then 15 years into their marriage (and 20 years since her cheating took place) and with 3 kids, Tom begins coming home drunk and cheats for other reasons; midlife crisis. Tom briefly fell in love with the other woman, stole some of his wife's money to spend it on his affair, secretly gave his wife's meals to the other woman and was thinking about setting up a trip to France just to be with her for a bit, away from responsiblities, away from the kids, out of reality. Their ages by then are 39 and 40.