Chris is Julia's boyfriend during part of her separation from Joel.
A "Chris Mollo" is briefly mentioned by Julia when she confesses to Sarah that she has slept with Evan Knight. It is possible that the writers changed Chris's last name to Jeffries, as it is implied that he is the ex-boyfriend of Julia.
In the beginning of Season 6, viewers see that Julia has begun dating Chris. The two dated in college, and it is implied that they may have also been together in law school, as Chris says, "I should have never let you go in law school." While Julia seems to be casual about the relationship, Chris tells her that he wants to make something of it. As the two get more serious, Chris realizes that Julia is holding back because of her marital status being unclear. When they go out to eat at a fancy restaurant, Julia spies a mom from Sycamore and is afraid that there will be more gossip about her. Chris is invited to a family barbecue by Adam, and Joel appears to say hello.
Chris, who does not usually cook or grocery shop, offers to do both in order to be more compatible with Julia.