Do you think you married 'the one'? Do you ever have doubts?

Honestly, i felt that my marriage is a great mistake. People date to know each other better before deciding on settling down with 'the one'. But my marriage is a dating period. Aft knowing my partner for 2 months, we got married due to having a kid (back then we were young and foolish) Right now, relationship is constantly on the rocks. Constant arguements on certain issues that we don't see eye to eye. I been asking myself, am i being the fickle minded one? or maybe this marriage is a mistake. Right now, going to 4 years of marriage. I still question myself....