In the original Arthur series, Bitzi revealed to Buster that Harry was her new boyfriend, in the episode Bitzi's Beau. However, just three seasons later, Bitzi and Harry broke up. Harry claimed that they world "remain friends," but that never works.
In an effort to make Bo jealous for remarrying, Bitzi decides to rekindle her relationship with her old boyfriend Harry. She sends him a letter, and they meet on a date. Breaking tradition, Bitzi gets down on one knee and proposes. Harry immediately accept, and they plan the wedding. Harry had no idea that Bitzi was just using him to get to Bo (I Wanna Marry Harry, Part 1).
The day of the wedding arrives, and Bo is shocked and disturbed at Bitzi's new-found relationship. He crashes the wedding and reveals to Harry that he is Bitzi's ex-husband. Apparently Bitzi hadn't told Harry earlier of her previous marriage. Harry is infuriated, and he calls off the wedding (I Wanna Marry Harry, Part 2).
After Volume 2Edit
It seems that Harry still had feelings for Bitzi after their failed marriage. He watched Bitzi's trial on TV (Trial and Error, Part 2), and gave the speech at Bitzi's funeral (Touched by an Angel). Harry wrote this poem for Bitzi: "Roses are red, violets are blue. You are now dead, but I love you."