It is similar to the the 'normal' persons crisis, except I believe it can be more destructive.
Usually some of the triggers can be:
Age, and physical aging.
The death of loved ones such as parents,
Children leaving the nest,
The Wiki has some of the Characteristics of mid-life Crisis::
- search of an undefined dream or goal
- a deep sense of remorse for goals not accomplished
- desire to achieve a feeling of youthfulness
- need to spend more time alone or with certain peers
They exhibit some of these behaviors:
- abuse of alcohol
- conspicuous consumption—acquisition of unusual or expensive items such as motorbikes, boats, clothing, sports cars, jewelry, gadgets, tattoos, piercings, etc.
- blaming themself or their partner for their failures.
- paying special attention to physical appearance such as covering baldness, wearing "younger" designer clothes etc.
- entering relationships with younger people
I'm sure that all Christians who have been a round a while would have seen the above behaviors with Clergy.
That when the incident is over and the minister has left the church. It would have been fobbed off as "Sin".