Kind of different for me, i was the one left behind.
No kids, so a blessing there but 9yrs of a relationship and an engagement ring. Thing is, it was pretty crap for ages. We had split up once got back together then pretty much exactly a year later she dropped the other shoe.
It nearly destroyed me but as time went on i realised that not only had we stopped having sex a long while back but that i didn't actually like her (nor her me). In the end i was clinging on because i thought that "this is the best i can do" and that i would suffer financially.
Her leaving was the best thing to happen in that relationship for about 5yrs, it creeps up on you so slowly that you accept the lack of sex/closeness/togetherness as being normal. It's only when you step outside of it that you realise what you are missing out on.
Although i did go through a period of clinical depression and lost my job into the bargain, i came out the other side happier, financially better off, with a woman who loves all of me and three more bikes!