When Marge had to work as the second income provider because of Eric and new expenses, she let Bart and Milhouse have limited babysitting with Maggie. At first Bart was reluctant because he didn't want that little "tag along" ruining his fun, but when Maggie wowed the boys with her skateboarding abilities, they decided to let her steal the show. Unfortunetly by this time, Lisa and Milhouse was starting to grow apart and they broke up under bad terms.
A few years later when Maggie was 19, she met up again with Milhouse at a coffee shop and they struck up a conversation. Realizing she had a crush on Milhouse, Maggie learned he was single and they, despite Marge and Lisa's objections, decided to date. A year later they were married. With the family's skepticism behind them, Maggie and Milhouse are quite the happy couple with their 5yr old son, Aaron.