Why were April and Andy allowed to date in Parks & Rec without issue, but Leslie and Ben couldn't? Parks & Rec, focusing on the Parks Department in the fictional city of Pawnee, Indiana, ran on NBC from 2009 to 2015. The Mike Schur and Greg Daniels-created show had a number of memorable romantic pairings, with Leslie and Ben & Andy and April being the most popular. At a glance, there seems to be a double standard when it comes to the two couples. However, there is a reason why Leslie and Ben couldn't date, but Andy and April could.
When Ben (Adam Scott) first arrives in Parks & Rec season 2 to audit Pawnee, Leslie (Amy Poehler) hates him, though the two soon develop mutual respect for each other and strike up a friendship in season 3 that soon turns romantic. However, Chris Traeger (Rob Lowe) has rules against inter-office dating, so Leslie and Ben make efforts to hide their relationship. On the other hand, Andy (Chris Pratt), who is a shoe-shiner at Pawnee City Hall in Parks & Rec season 2, starts dating April (Aubrey Plaza), who has a job as Ron's assistant, and they eventually get married in the season 3 episode "April and Andy's Fancy Party."
The reason why Leslie and Ben couldn't date but April and Andy could is because of the difference in workplace roles for both couples. Ben is Leslie's boss, so the two of them dating would create a conflict of interest. However, Andy is not technically an employee of the government, so he and April are allowed to date. Though Andy does eventually become Leslie's assistant during her city council campaign in Parks & Rec season 4, he and April are married at that point, so there's no issue with them being romantically involved in the workplace.
In an interview given after Parks & Rec's season 3 finale (via Uproxx), Mike Schur explained his reasons for keeping Leslie and Ben apart:
"The “no dating” thing is a very big deal in government – these people are handling taxpayer money, so relationships are even more frowned upon than they are in the private sector. There was realism to the obstacle, which was key, and more importantly it seemed like with Leslie and Ben, two people who care very deeply about their work, the idea that work itself is keeping them apart would be nicely ironic."
The workplace rules keeping Ben and Leslie apart are an interesting dramatic obstacle to their relationship in Parks & Rec, especially when Leslie Knope is seeking a City Council position. It also leads to some amusing moments of Leslie and Ben attempting to keep their relationship under wraps. The fact that Ben and Leslie manage to overcome these obstacles (with Ben even quitting his position so he can save Leslie's job) is heartwarming and makes their relationship stronger and better. By the time Ben is promoted to City Manager in Parks & Rec season 6, his relationship with Leslie is also no longer an issue, since the two of them are married.
It made sense that Leslie and Ben weren't allowed to date while they both had roles in the Pawnee government, as the workplace rules are realistic for the type of environment Parks & Rec is set in. The same rules don't apply to Andy and April because there's no conflict of interest in their relationship. Ultimately, it's good for Parks & Rec that both of these relationships were allowed to be happy in the end.