a/the honeymoon period
The short amount of time at the beginning of a new relationship, activity, or pursuit when everything goes well and seems to be free of problems. Donna was excited when she started her new job, but once the honeymoon period was over, she realized that she had more responsibilities than she could handle. Many couples find it difficult to maintain a relationship after the honeymoon period ends.
a/the ˈhoneymoon perioda period of time at the beginning of something, for example a relationship, a job, a period in government, etc., when everybody is pleased with you and there appear to be no problems: The honeymoon period is over now for the new President.
honeymoon (period)and honeymoon stage
n. an early stage in any activity, before problems set in. You’ll know the honeymoon period is over when everything seems to go wrong at once. Of course, this is still the honeymoon stage, but everything seems to be going all right.