Former Scottish International rugby player Thom, is said to have called time on his seven-month relationship with the 90210 actress because of long distance, The Mirror states.
A source told the newspaper: "It was a mutual decision and Jessica and Thom have been on and off for quite a while now."
Jessica lives in Los Angeles, while Thom is continuing his modelling work in the UK. The couple's rumoured break-up comes two months after Thom's ex Kelly Brook split with Danny Cipriani, who also used to date Jessica.
The source added that Thom and Jessica have "hardly seen one another" recently, adding that it was "totally unfeasible" for the pair to maintain a relationship across the pond.
Jessica and Thom were first romantically linked in February, but in April, 24-year-old Jessica confirmed their romance by posting a series of intimate photos of the pair on Instagram.
In the same month, Jessica enjoyed a lengthy stay with Thom in London, where she took in the tourist hotspots of the capital.
Speaking about their blossoming romance in May, Jessica told Reveal: "He's just wonderful and very sweet and polite".
Meanwhile, Thom said: "It's going good between the two of us. We're just really happy."
Reveal have contacted their reps for comment.