She super sized her man!

Sofia Richie treats Scott Disick like the king he thinks he is, as evidenced by the fact she swung through McDonalds and picked him up some fast food while he was busy negotiating a deal at the car dealership in Calabasas yesterday. Hopefully she didn't forget his dipping sauces!

We've gotta hand it to the teen model... she's been able to accomplish the impossible, by making LD a one-woman man! It feels like just yesterday he was with Kourtney Kardashian and cheating on her every time she turned around, but we're starting to buy that he's a changed man!

In fact, insiders tell us that the bad boy father-of-three is more stable than he's been in years, in large part due to the loving support he gets from his girlfriend.

A source tells X17:
    "Sofia has been such a stabilizing force in Scott's life. You wouldn't be able to tell by his behavior, but he's actually a really insecure person with low self-esteem. When he was with Kourtney, all she did was nag him and point out all of his flaws, and it made him lash out to get validation. With Sofia, she's constantly building him up and showing him how much she loves him, and it's given him a new level of self-worth."

We never thought they'd last this long!