Scott, 32, and 36-year-old Kourtney ended their relationship last week, and it is believed he still hasn't returned to the family home.
Yesterday he took to Instagram to share a collage of pictures of Penelope, writing: "1 of the only things I'm proud off about myself. Happybdayp [sic]."
His message to Penelope suggests Scott is feeling remorseful, after he was snapped with his rumoured ex-girlfriend Chloe Bartoli in St. Tropez.
Keeping Up With The Kardashians star Kourtney put on a brave face yesterday and treated Penelope to day out at Disneyland, joined by sister Kim, 34, and her niece North West.
New reports have claimed that Scott, who also shares Mason, five, and six-month-old Reign Aston with Kourt, is rebelling against family life after three children apparently became too much for him.
A source told People magazine: "He loves his kids. But he was never ready to be a stay-at-home dad.
"Scott rebels against the crazy responsibility of having three kids."