Some people prefer to be alone. Some people prefer not to be alone. Whether or not you can accept a loner lifestyle depends mostly on your preference, which is not directly under your control.
Preferences are rooted in very complex arrangements of different factors. If people could directly control their preferences everyone would be living a perfectly healthy lifestyle and be in loving relationships and there would be no violence, poverty, etc. The idea that you can directly alter most of your preferences is a pipedream. It may happen that, through various circumstances, and various reframes, your preference changes, but it's not the kind of thing that anyone can tell you how to do. Everyone got to their preference through idiosyncratic ways that won't work for anyone else. You can't give everyone in the city the same directions to the store -- turn left, walk 2 blocks, turn right, etc. -- because everyone's starting from a different location.
So, is it possible to live a happy life without ever being in a romantic relationship? Yes, it does happen. Lots of people are happier that way. But people also win Nobel prizes and Olympic medals. There's a difference between "possible" and "likely". For most people, it's easier to get into relationships over and over again until they find one that works than it is to be happy alone. That's why our culture is obsessed with romance. (It has nothing to do with brainwashing. It's just basic human psychology.)
But some people are never going to find their way to accepting it, or accepting certain other things. And trying to find that acceptance, instead of trying to satisfy a preference, when satisfying that preference is equally possible, can be very destructive. (For starters, it can be a way to avoid dealing with the problems that are preventing you from finding a relationship, effectively consolidating your dysfunction instead of eliminating it.)
If you're trying to change your preference you have to be very clear before you start whether or not you're indulging in self-harm or unhealthy thinking. Because, ime, most of the time, that's what trying to change a preference amounts to.
Wishing she had a mindblowing GUI