"Days of Our Lives" fans know that Chad and Abigail have been through a lot in their relationship. They began dating at a young age, but eventually called it quits when Abby found out that Chad had lied about having a brain tumor to get her sympathies (via Soaps in Depth). Chad moved to Boston, where he lived for a while until he found out that Abigail had a torrid affair with his older brother EJ DiMera (then James Scott). Chad returned to Salem angry with both Abby and EJ for their behavior, per Soap Central. This is when Billy Flynn first captured the attention of "DOOL" viewers.
At the time, the role of Abigail was being played by Kate Mansi, and fans couldn't get enough of her chemistry with Flynn. The pair grew close again, and even welcomed a child together. However, Mansi eventually decided to leave the soap opera, and the character was recast when actress Marci Miller stepped in to take over. Fans grew to love Miller as well, but when Miller left the show, Mansi returned for a short stint. Mansi opted to exit the sudser again, leaving Miller to return to the character (via Soaps in Depth).
While fans appear to like both Miller and Mansi in the role of Abby, Flynn says it's been difficult for him to work with all of the changes.