According to OK magazine, the pair called it quits because they are undecided over when to have kids.
'He wants kids and doesn't want to keep putting it off but it's not quite the timeline Miley had in mind...he is left heartbroken,' the source said.
'Miley put off plans for the wedding and Liam was growing tired of it... They haven't been getting along in recent months.'
This could be why Miley recently went rogue and deleted everything from her Instagram page.