This wikia page is about Stuart Dunmeyer, a secondary character in Mrs. Doubtfire portrayed by actor Pierce Brosnan. Although unusual for a wikia entry, It includes both summary and possible character analysis.
Stu Dunmeyer was about 39 years old and he was seeing Miranda Hillard. He stated he was crazy about Miranda's kids and especially little Natalie. Also, he called Daniel Hillard a loser father figure, which, while true, did not apply to his love for his children.
As he said to a barman at the pool, he didn't want to spend the rest of his life alone and so he started seeing Miranda. Mrs. Doubtfire, a.k.a. Daniel, was keen on trying to keep Miranda from Stu. Stu is allergic to pepper and in the Bridges Restaurant, he sprinkled pepper on Stu's ready-to-go jambalaya.
Mrs. Doubtfire pulled the Mercedes badge off Stu's car and called it a car for Don Juan. In the restaurant, Mrs. Doubtfire was being somewhat graphic about Stu in Miranda's bedroom and said she had a power tool. This could mean Daniel Hillard maybe still loved Miranda but did not show it or he did not want another father figure in the childrens' lives. Due to Miranda initiating the divorce, both theories could be true.
Natalie quotes that Stu's stomach is different than Daniel's. She could be hinting that she maybe does not like the idea of Stu being with Miranda.
Not much is known about Chris and Lydia's relationships with Stu but they may not like him since Mrs. Doubtfire is Daniel, their dad.
Obviously, Mrs. Doubtfire does not like Stu but Miranda does.
His last appearance is in the restaurant, being taken care of by Daniel after choking on his food. His lack of presence in the film may signify a breakup, that he is in the hospital due to Daniel's food tampering or that he is simply not present.