I have seen many folks say that a good marriage is the enemy of a great marriage (for example, How to go from good to great in marriage ) and I couldn’t agree more. The issue is risk aversion. Studies have found that most people go for the lower risk option even if the “pay-off” is lower. Additionally, we tend to value what we have more highly than what we don’t have.
Certainly these tendencies are good – it keep us from taking stupid risks. Unfortunately, it can also keep us from pushing for growth, for being better. Say you’re not really happy with your marriage (or sex life, or job, or whatever) but you are not horribly unhappy with it either; rather than risking what you have to obtain something far better, you convince yourself that what you have is okay.
At best this means you live with barely good enough. Often it’s worse than that – you accept things that really are not enough, and as the months and years pass, resentment grows. This is why men “suddenly” tell their wives they will leave if there is not more sex immediately – even though the amount of sex has been consistent for years. This is also why a woman “suddenly” leaves a marriage even though nothing has changed.
Are you accepting something in your marriage that is not really enough? Is it possible your bride is? Either one of these will slowly kill your marriage from the inside out.
The other aspect of this is that usually it’s not an “all in” win or lose choice. If you have a good marriage and a reasonable spouse, trying to improve your marriage should not put what you have a risk. The link above has some good ideas on ways to go from good to great.