Kim Kardashian has warned her sister Kourtney she faces losing her boyfriend unless she pays him more attention.The 32-year-old star issued the relationship advice to her older sibling, despite having a failed marriage to Kris Humphries which lasted just 72 days.On a preview of their reality show 'Kourtney and Kim Take Miami' she insists Scott Disick will cheat on her if she doesn't show him more affection and says it will be her own fault if he does.She said: "'He's gonna cheat on you and it'll be your fault. You just don't put in any effort. You're going to lose him. No joke."He just feels like you only care about the kids."You're literally going to end up, like, alone."The 33-year-old reality star - who has children Mason and Penelope with Scott - is later seen voicing her concerns about her relationship.She said: "For me, I like doing stuff all together as a family."Just hearing Kim say those words really just freaks me out."Not that Scott would ever cheat on me, but I just really don't want this for my relationship."