Can blackbird pairs split up?

Hello, 

A pair of blackbirds have had their territory in my garden for the past few years now, finally raising their own young this year. I can tell the pair in my garden very distinctively from others, as they are both on the larger size. 
As of a week ago, they have seem to become very aggressive to each other, fighting and squabbling constantly. To the point where I witnessed the female pecking/biting the male. I know blackbirds can mate for life so can they also split up/divorce? Is this normal behaviour? 

Thanks