Honestly, I think it's because we now live in a disposable society. So disposable that we apply the same mentality to people from what I see. Why work at fixing something when it's broken when you have it replaced with something shiny, new and with better features? Plus, we've taken looking out for number one (ourselves) too far. We have forgotten the preciousness of unity and honouring a promise. We have also forgotten the art of being romantic and affectionate. Both men and women. I walk down the street arm in arm with my husband and people stare at us like we're doing something inappropriate. To me, that's the greatest sign of all that affection and being romantic is a lost art.
Don't get me wrong, some reasons are valid, but I find it very strange and unrealistic that everyone just "grows apart", "is unfaithful", "changed" or whatever. If we can work our posteriors off at working with someone we don't even like at work, we have no excuse to fix things with the spouse/significant other we have if there's no abuse and the problem is fixable.
And as for cheating, at the risk of sounding bold, it's a fixable thing. I don't deny that it hurts and you can't forget it, but you also have to remember that you can even be a repeat offender and still love your spouse to the point of bending over backwards repeatedly for them. Most people cheat because they have issues with themselves so they turn to a side lover the way some people turn to the bottle, food or drugs. It's an attempt to numb pain in secret rather than face the shame of admitting they have problems. It's also why some cheaters are repeat offenders. Their real problem is never solved so of course they continue to cheat.
At least that's my two cents as a married woman. And for the records, I've never been cheated on, but I've known a lot of people who suffered it and committed it and I can confirm they are not simply people who fell in love with someone outside the marriage. They are miserable people who hate themselves.
