There is so much on here about what makes a good enough marriage or long term relationship.
What about if you get on well, do not really argue, have a good partnership with children who are doing well and all the other things.
But - there is a lack of passion and you don't really feel any romantic or sexual feelings towards other half. In other words, the relationship is based on friendship. The fancying/romantic element has gone.
Stay in it for security, sake of children, keep the peace? Or go in search of passion?
(Have already read Madame Bovary and Anna Karenina).