From my observations, once it's over, it really is over. Especially for the woman (not by chance, women initiate divorce 2/3 of the times).

When she feels no attraction, no desire and no more emotional connection with her partner, I'm afraid the fire is gone and cannot be rekindled.

Humans are NOT a long-term monogamous species (even Dr. Psych Mom admits this). We're fooled by society into thinking that "marriage is forever", but nowadays it's definitely not. Sooner or later we find ourselves stuck into a boring and lukewarm (at best) relationship, burdened by chores and a mortgage, and feeling more and more alone - not to mention sex-starved, of course.

When you feel it's really over, I'd say better cut your losses and move on (*) - yeah, try couple counseling first, but I wouldn't hold my breath.

When there are kids, though, it's easier said than done.

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(*) Beware of vindictive ex-wives and lawyers, though! If you're a man, don't expect the system to be fair towards you.