Because everyone is on best behavior during a date.
There's the amount of attention that's desired (or downright required) to make each other happy; the time not spent in the same place, let alone physically together; and the attention that needs paying to other people who theoretically have nothing to do with the relationship.
It's a lot to juggle, and while some couples simply implement the two-week rule and go on about their business, others are going to butt heads no matter how much care they pay to logistics or even how in love they are (or how in love they started out).
While drinking with Lynette in a hotel, Annie says that Mrs.
X (her employer) dumps all of her problems with her husband onto Annie. "Denial" is one of the psychological defense mechanisms proposed by Freud whereby a person refuses to accept a reality. X's behavior is not denial, instead it is another defense mechanism called "displacement".
After graduating from Montclair State, New Jersey Girl Annie can't make up her mind about what to do with her life.