Entertainment TV Sofia Richie Shares Steamy Kiss with Scott Disick in Mexico Declaring Kourtney Kardashian's Ex Her 'Boyfriend' Scott Disick's relationship with Sofia Richie heated up in Mexico while Kourtney Kardashian returned to Los Angeles to be with their kids By Alexia Fernández Published on October 2, 2017 09:35 PM Share Tweet Pin Email Photo: HEM / BACKGRID It seems Scott Disick and Sofia Richie are getting closer than ever. Disick, 34, and Richie, 19, spent most of Monday soaking up the sunshine in Puerto Vallarta, Mexico, – and indulging in some serious PDA. Their steamy romantic vacation comes as the couple’s relationship heats up, a source close to Disick tells PEOPLE. “Scott likes having her around,” the source says. “She isn’t a wild party animal.” The source says Richie more than just likes having Disick around with the teen putting a label on their romance. “Sofia calls Scott her boyfriend,” the source says. “She thinks he is the best.” Calling Disick her “boyfriend” is certainly a far cry from what Richie called them in May, tweeting out that the two were “just homies.” Despite Richie giving him a label, the source says the father of three isn’t ready to completely plunge back into a relationship. “Scott likes her, but still says it’s not serious,” the source says. “Sofia hasn’t met his kids.” Richie is certainly not being shy about their union, with the 19-year-old sharing a photo on Instagram Monday of herself and Disick cuddling by the beach in Mexico. RELATED VIDEO: Scott Disick and Sofia Richie Get a Congratulations Dessert and Become Instagram Official While the pair shared PDA aboard a jet ski, Disick’s ex Kourtney Kardashian, 38, returned to Los Angeles following her Paris getaway with boyfriend Younes Bendjima, a source tells PEOPLE. “She had another amazing vacation with Younes, but she really missed her kids,” the source says. “She seems very excited that her sisters are pregnant. They are all already talking about baby showers. Khloé and Kylie are asking for baby nursery advice. It’s like it’s bringing the sisters even closer together.” The pregnancies of Kylie and Khloé were revealed just days from each other, with older sister Kim Kardashian West confirming she was also expecting a baby, her third, via surrogate.