Contrary tothe movies, popular culture and the Bachelor/Bachelorette TV franchise, having a happy life requires more than a loving relationship with a partner. Putting all your relationship eggs in one basket may put too many expectations and too much pressure on your love relationship.
I like the Buddhist saying, "before enlightenment, chop wood, carry water; after enlightenment, chop wood, carry water." The same is true about life before and after finding a life partner. Both before and after, we need friends, hobbies and passions, interests of our own, work that is meaningful, an exercise and self-care plan, a spiritual life, and the ability to spend some time alone.
When people are dating, they often are looking for someone who will make them happy and fulfilled. When people fall in love, their world often revolves around the beloved for some time. At some point, a few months or a year or two into the relationship, most people realize that they will suffocate each other if they don't also balance the couples time with time with other friends and activities. The truth is that even happy couples don't stay perpetually "in love." Over the course of a long-term relationship, couples often go through phases of feeling "in love" and not. That's normal.
Happy people realize that being in love or happily partnered doesn't mean to demand or extract your happiness from that other person. You are still responsible for your own happiness, sense of purpose, developing yourself, and keeping connected to healthy friends. As it turns out, some separate activities and interests can keep things interesting. (Think Paul Newman and Joanne Woodward, who were happily married despite his passion for car racing, and her love for ballet. They were happily married over 50 years before Newman's death.)
Maybe happily ever after looks more multi-faceted than we were led to believe. Readjusting expectations of marriage and couples' relationships is healthy. Developing a healthy, sustainable love relationship is just a part of the bigger picture of building a happier life.