We don't blame you if you've forgetten that they had ever broken up in the first place, tbh we forget sometimes too but Miley has revealed why they called off their engagement back in 2013.
While on The Howard Stern Show Miley was asked why she broke up with Liam back in 2013:
I had to, I don't like when relationships are two halves trying to make a whole. I don't think I have that codependency.
But the breakup wasn't all bad, obviously they're back together now but Miley talked about how the breakup helped her grow as a person:
You get time to be yourself. You get time to grow up. I think if you're growing up attached to another person, you never really get solid as your own being.