Blake Shelton and Miranda Lambert had had ''issues for years''.

The couple announced earlier this week they were to split after four years of marriage but friends of the country stars were not surprised by the news as their problems have been growing increasingly worse over the last few months.

A source said: ''They have been having issues on both sides for years now, but in the past few months it had come to a head. Blake and Miranda just grew apart and really started not seeing eye-to-eye on some real life future plans with each other.''

And despite only breaking the news this week - hours before the divorce was finalised - the 31-year-old singer and the 'Voice' coach had been leading ''separate lives'' for some time.

The source added to E! News: ''Miranda and Blake have known this divorce been coming for some time now.

''They had not been together for a while and were living separate lives. They were just trying to find the right time to break the news to the public.''

Though they want to be friends one day, Miranda and Blake, 39, are planning to give one another space for the forseeable future.

The source said: ''Their family and friends feel this decision is the best for them...They both hope in the future they can remain friends, but for now, they both know that after this divorce they need space and time to just be alone and not in [touch] for a bit.''