Who are Luke’s previous romantic interests?
One of the youngest characters, Luke started showing the first signs of interest in women during Season 4, during the episode titled “New Year’s Eve.” Becca (Paris Smith) and he attended the same party, but the romance didn’t escalate any further.
Luke also had crushes on various young women throughout the years, most notably Simone (Olivia Rose Keegan), who appeared in “Best Men,” and Carly (Courtney Grosbeck) in “Suddenly, Last Summer.”
Some of his other, laudably ambitious albeit similarly futile romantic attempts were with Sienna (Madison McLaughlin) whom he developed a crush on in “A Fair to Remember,” Rhonda (Arden Bell) in “Spring-a-Ding-Fling,” and Tammy Lafontaine (Brooke Nicole Sorenson), whose family lived right next to the Dunphy household.
Source : https://www.distractify.com/p/modern-family-luke-girlfriend