He knew Simpson was "the one" after about four months of dating.
Ross went public with his romance with Jessica Simpson's younger sister last July. Insider that she was "the one," and marriage was "for sure" in their future.
The 24-year-old hunk wore a polka dot scarf, trendy shades and a casual black tee, sporting a hipster cool look to keep up with his fashionable gal.
Last September, Jessica shared a photo of the two in their dresses on Instagram, writing, "I am madly I love with this moment!
" In addition to members of the Simpson and Ross families, the guest list included longtime Simpson family friend Ca Cee Cobb and her husband, Donald Faison.
This "Supremes" scion, like his mama, can also sing! In the past, Ross was rumored to have dated Aubrey O' Day, Lindsay Lohan, Hayden Panettiere and costar Hilary Duff.
Ross began recording his debut album in 2007, and released his first single, "Yes Me," in February 2011. PHOTOS: Ashlee Simpson and Pete Wentz, the way they were 5.
While working on her debut studio album, Simpson became the star of her own spin-off reality series, The Ashlee Simpson Show (2004–05).