The 34-year-old Keeping Up With the Kardashians star and Kourtney Kardashian's ex and Lionel Richie's 19-year-old daughter, a model, had sparked romance rumors in May when they got flirty on a yacht around Cannes, days after he was spotted getting cozy with a few other women. Sofia later tweeted she and Scott are "just homies."
In June, they were spotted FaceTiming each other. In September, they spent time together in Santa Barbara and were also seen kissing on a trip to Miami, where they went out to dinner and received a cake with the inscription "Congratulations Scott & Sophia." No explanation was given. That month, E! News learned the two were hooking up but were not exclusive.
"From Scott's side, it's not serious. From Sofia's side it is," a source close to Sofia told E! News exclusively on Friday.
"She calls Scott her boyfriend and they spend as much time as they can together," the source said. "Scott likes her company because she is mature for her age and doesn't party much. She has actually been really good for him. They have traveled a lot, but they also do normal things like get coffee or go shopping. They are mellow together and just really enjoy being low key. He has spoiled her by taking her on a few amazing trips and she has loved that. They have experienced a lot together and had some fun adventures in a short time."
Scott and Sofia have not commented on the status of their relationship.
In September, another insider close to Sofia told E! News that Scott and Sofia "are inseparable right now and not leaving each other's side."
"He is taking care of her and that's exactly what she loves," the source had said. "Sofia has been interested in him for a long time. She feels like she knows a different side of him and that they are good for each other. She is falling hard and thinks this is the real thing."
Earlier this month, her famous dad talked to Us Weekly about the pair.
When asked if he was happy for the new couple, Lionel said, "I'm scared to death, are you kidding me?"
Watch a brand new episode of Keeping Up With the Kardashians Sunday at 9 p.m., only on E!