Miley Cyrus stops following fiance Liam Hemsworth on Twitter

IN YET another sign that their four-year romance is in a slow, painful and ultimately terminal spiral, Miley Cyrus has taken the drastic step of unfollowing fiance Liam Hemsworth on Twitter.

Cyrus stopped following Hemsworth just days after Us Weekly claimed he was wooing Mad Men actress January Jones behind her back.

The pair's relationship has been plagued by breakup rumours for months. Us Weekly now reports Hemsworth and Cyrus "are just weeks away from calling it off permanently".

Hemsworth was reportedly "mortified" by his fiancee's raunchy performance at the MTV Video Music Awards last month. Cyrus stripped down to flesh-toned underwear and twerked against male singer Robin Thicke.

Still, we can't imagine why Hemsworth would want to abandon his relationship with such a lovely young lady. Or, for that matter, why Cyrus would want to admonish her fiance so indirectly for chasing another woman behind her back.

Sigh. Love. It's a mystery all right.

Miley Cyrus performs at the MTV Video Music Awards. Photo: Charles Sykes/Invision/AP

Cyrus's Twitter-based vengeance is not unprecedented. Fellow singer Katy Perry made headlines last year when she unfollowed estranged husband Russell Brand after he filed for divorce.

That's the 21st century for you. No breakup is truly official until it's Twitter official.