Selena Gomez and Justin Bieber

Selena Gomez and Justin Bieber

Justin Bieber has been "doting" on Selena Gomez.

The 20-year-old singer has been pulling out all the stops to win back the 'Come & Get It' hitmaker - whom he has been dating on/off for three years - by showing her that he can be a true gentleman.

A source told PEOPLE.com: "Justin's extremely doting on her, and there hasn't been one second where he hasn't been touchy-feely and sweet with her. They're pretty inseparable and very affectionate."

The 'Baby' hitmaker took the 21-year-old beauty to Los Angeles Zoo yesterday (22.06.14) as part of a double date with his maternal grandparents Bruce and Diane Dale, and made sure he "stayed close by Selena's side" as they took in the sights at the animal park.

Last Friday night (20.06.14), Justin also treated the 'Spring Breakers' actress to an expensive meal at the upmarket steak restaurant Mastro's in Beverly Hills, California, before taking her to the cinema at the nearby Westfield Century City mall, to see the new comedy, 'Think Like A Man'.

However, Justin has not just spoiling Selena, whom he began dating in 2010, with romantic dates as he also presented her with a £6,000 Segway last week in a bid to prove they could have "good, clean fun" together after recently vowing to curb his wild ways for her.