Romo, 28, and Simpson, 27, have been dogged by rumors that her father has been meddling in their nearly seven-month-old courtship.
In his statement, Romo insisted that characterization is "so far from the truth."
A source also confirmed that Romo's father, Ramiro, went to the Masters golf tournament in Augusta, Ga., with Joe Simpson earlier this year and "had a great time."
And there was more family bonding when, after spending a couple of days in Dallas, the singer and Romo shared a lunch date Friday with pregnant sister Ashlee Simpson and new husband Pete Wentz at a Chili's in Encino, Calif.
"Jess was giggling and grabbing onto Tony. They were both very natural and sweet with each other," says a source. "It was cute to see the sisters and their guys having such a good time."
Reporting by JENNIFER GARCIA