imo i feel that if your relationship is failing and all hope of reconcilliation is lost, all avenues have been explored,nothing can be done, then divorce because of the kids. kids are not stupid, and they can sense tension and discord. mom and dad not sleeping in the same bed or room, is not comfortable for them, they may not know why it's wierd, they just know it is. my parents divorced, it was horrible and awkward and sad and when all the dust had settled, way better. no tension, no tiptoeing on eggshells. and they weren't happy, their marriage failed, they were single, again. but all the stress and anger was gone and they could move on. i'm a big believer in ripping the bandaid off.
what i see happening all to often is people giving up and not fighting for their marriage. they don't want to compromise, they want to be right. it's hard sharing your life with someone and thinking that love will save the day is setting oneself up for a huge fall.