Kendall Jenner's relationship with boyfriend A$AP Rocky has become ''more serious''.

The 21-year-old model has yet to confirm she is officially dating the rapper, but the pair have been spending a lot of time together and it is rumoured their romance is starting to get increasingly more intense.

Speaking to PEOPLE about the couple, a source said: ''They're definitely still hanging out and are progressively getting more serious.''

The catwalk icon was accompanied by the 28-year-old artist - whose real name is Rakim Mayers - to her half-sister Khloé Kardashian's 33rd birthday bash at the West Hollywood hotspot Blind Dragon, and during the party the duo could not stop ''canoodling'' with one another.

The source explained: ''He showed up at Khloé's birthday at Blind Dragon after the BET Awards to show his support for Kendall, her sister and the rest of the family.

''They were canoodling in a booth.''

The 'Keeping Up With the Kardashians' star and the 'Wild for the Night' hitmaker even enjoyed a duet together during the karaoke session.

The insider added: ''And [they were] singing live music together.''

It has been reported the raven-haired beauty and A$AP Rocky have been friends with one another for a long time, but their friendship progressed in 2016 when they were spotted in Paris, France, together.

And at this year's Coachella Valley Music and Arts Festival the fashion muse was spotted rapping to A$AP Rocky's 2013 hit single 'F**kin Problems', much to his amusement.

Speaking about Kendall's antics at the annual music extravaganza, a separate source said: ''Kendall showed up with a posse just for him and they were all over each other.

''Kendall started rapping to A$AP's song 'F***in' Problems,' and A$AP was laughing at her. She took the big Gucci goggles he was wearing off his head, put them on and started dancing.''

However, the television personality struggles to ''settle down'' with a lover because of her hectic work schedule.

Another source previously said: ''It's hard for Kendall to settle down still because her schedule is so crazy and she's always traveling ... but she's as 'settled' as can possibly be at this point with A$AP.''