When Erin and Chad told John and Olivia that they were going to get married, John said that Erin needed to finish high school before they could marry.
Thus, Chad and Erin eloped to the local judge's home, waking them up in the middle of the night. The frustrated judge begins the ceremony, giving Chad and Erin dirty looks. When it was time for Erin to say "I do", she ran out of the room crying. She told Chad that being married was supposed to have flowers, family, and joy! Not being glared at by some judge.
Then John and Olivia came, (they soon found out that Erin and Chad eloped), and took Erin home.
Chad never did marry Erin, but they both spent time together sometimes.