All these years have made me realise, there are four things in life you can't get too bogged down in: forever, morality, virtue, and life and death.
Insistence can sometimes be a virtue. But if you insist too much on 'forever', your fear of losing someone will blur your vision; if you insist too much on 'morality', it will just become a stubborn obsession, most things are not so black and white; if you insist too much on 'virtue', you will become conceited, and try to change the rules to suit your values; if you insist too much on 'life and death', you're dwelling on the insignificant, and you would just be living a second-rate life.
There are just some things that ought not to be questioned, ought not to be dwelled upon. What's done is done, whether it was right or wrong matters not. Wouldn't you rather think about the future?