Kendall Jenner and Blake Griffin have ''cooled off'' their romance.

The 22-year-old model and the NBA star were growing closer to one another since they began dating in August last year, but after Blake was traded from the Los Angeles Clippers to the Detroit Pistons, the long distance between them has meant the pair have ''grown apart''.

A source told People magazine: ''They've definitely cooled off and are taking things at a slower pace, but not because of any particular drama. He got traded and isn't local anymore, so they've grown apart a bit just because of distance. They're still involved.''

Their slowed down romance comes after it was previously revealed the 'Keeping Up with the Kardashians' star was ''serious'' about the 28-year-old basketball player.

In November, a source said: ''Kendall was in a great mood [at her party]. She and Blake hung out, but they also mingled separately ...

''Kendall is very happy with Blake. They started out more like friends, and then it was very casual. But it seems more serious lately. When they are not together, they keep in touch over the phone. Her family has accepted Blake. They are spending time getting to know him.''

Kendall began seeing Blake after calling time on her romance with ex-boyfriend A$AP Rocky, but it was previously reported Kendall had been ''playing the field'' in the early stages their relationship.

A source said: ''Kendall and Blake have been hanging out quite a bit and are having a good time. They met in passing a few times and hit it off. She's still talking to Rocky as well. But he isn't the type to settle down or be a good boyfriend, so she's playing the field too. She's seeing Blake romantically. It's nothing serious. She has been in LA a lot lately, and is having fun.

''Work will soon take over her life again, so who knows what will happen will Blake then. She is having fun right now and that's all that matters to her. She takes her career very seriously and that's her number one priority right now. Kendall is keeping her options open. She's still dating A$AP Rocky as well, but she and Blake are hanging out, and there's potential there.''