The answers are:
- Not having open communication
- Experience an extreme pressure in professional life
A relationship would be considered as 'detrimental' if that relationship has a high chance of causing harm for all the people involved in the relationship.
When people does not have an open communication, we tend to keep the mistakes / annoying habits that other people do to us privately. Over time, this would lead to hatred toward that other individual.
Pressure on professional life tend to cause a stress. Often times, we tend to use people around us as an outlet to release our frustration, even if they do not deserve such treatment. This could also lead to detrimental relationship.