I had a discussion with a couple on a Sunday and all was about high expectations by lovers. Here is the excerpt;

Many lovers are growing pseudo romantic beliefs through the films they watch and the novels they read; to some, they expect their spouses to act like the Karishika they saw on a pornsite.They fail to realise that most of these people consume hard drugs and alcohol to stay long in the act; and also do it for money - a great source of motivation.

I presume the ideas of love at first sight, “love will overcome all obstacles,” and “happily ever after“ are great but they are only applicable to 1 in 100 relationships.Ask around from couples that have scaled through the hurdles and still learning, they have many great lessons to share with you.

Religion is also playing a major role in this issue.The teachings and beliefs that you should never fight with your partner and that you will always have amazing moments together sounds really cool. These beliefs culminates into high romanticism which leads to high expectations for your relationships: The problem is that with such lofty ideal standards for your relationship, you’ve set yourself up to fail because these unrealistic expectations are, well, unrealistic. There are ups and downs.There are moments you will look at your partner and want out.

The fantasy of a "perfect relationship" in reality are not absolutely applicable. The principles from teachings would guide you but you have to identify,define and develop tactics that would work out perfectly for your relationship, then you are ready for the race.
Self defined values and conviction ,mutual agreement,tolerance and God leading also have good role in achieving a great feat after all.