Scott Disick, 34, pledges to 'grow up' for Sofia Richie, 19, as Kourtney Kardashian unveils new look

Father of three Scott Disick, 34, is having to finally grow up and settle down for his 19-year-old girlfriend Sofia Richie.

The Keeping Up With The Kardashians reality star, who endured a tumultuous on/off relationship with Kourtney Kardashian for a decade, is said to be laying off the nightclub scene for his new beau.

Sources have told TMZ that Disick – who has garnered a reputation as a bit of a playboy for dating high-profile celebrities like Bella Thorne – has toned down his partying ways.

The change of behaviour was sparked by his romance with Lionel Richie's daughter. He doesn't believe the 15-year age gap is an issue as the model is used to the spotlight, because of her famous family.

The couple have already been on several holidays together, including to Milan, Miami and Mexico, and have chosen to enjoy date nights at low-key restaurants instead of nightclubs.

Disick – who has admitted to struggling with alcohol abuse in the past – has even told friends that Sofia has ''been really good for me".

Meanwhile, Disick's long-term ex Kourtney has been enjoying her new relationship with 24-year-old male model Younes Bendjima.

The working mother appears more in touch with her youthful side than ever, recently releasing a scantily-clad fashion line for Pretty Little Thing and showcasing her toned physique on Instagram.

Kourtney's most recent snap unveiled her new shorter hairstyle – otherwise known as a 'lob' (long bob) – to her 59.3 million followers.

Wearing a cropped white T-shirt with jeans, the star took a snapshot of herself in the mirror which showcased her 'Kimoji' phone case, featuring younger sister Kim's famous crying face.

She captioned the shot: ''don't worry, i ordered a new phone case last night.''

Fans were quick to comment on her new look, with one person commenting: ''Short hair ??? Really ????? Im SO tired But you're beautiful''.

Another said: ''You look younger with this length of hair,'' while a third added: ''Gorgeous natural woman''.