Most people assume that if they separate from their significant other for college, military, work, etc, that the relationship will fail. With this being said, the same people also assume that it is better to just end the relationship now than to even try to make the relationship work. Whether you're one of these types of people or you have a different situation, long distance relationships CAN work.
Typically the main reason for long distance in the younger generations is college. This being said, college is also known as a place to party and have fun, right? Since college is a place to party and have fun, that means your significant other is going to do just that, right? And since your significant other is going to do just that, they will end up cheating, right? Wrong. The main cause of failed longed distance relationships is almost always failed trust. Being away from someone you love is never easy, but you have to trust that they love you just as much as you love them. Put yourself in their position first, would you ever do what you are "assuming" they would? If not, and if they love you as much as you love them, chances are neither would they. You have to trust that they would never do anything to hurt you because they love you.
The second problem most long distance relationships have is assumptions, as talked about above. Many couples tend to assume that their significant other did something, without even asking them if they did or not. And once they ask, they also tend not to trust what they say. When you live so far apart from the person you love, you have to communicate with them and trust their response instead of relying on what you may have heard from someone else, after all, it is about them. Overthinking which leads to assumptions will surely hurt your relationship, not help it!
Lastly, if you are in a long distance relationship you must communicate with each other. Not talking for days at a time and then believing everything will be normal and okay when you do talk is not very realistic. By this, I don't mean just texting, call each other. Really talk. Communication is a huge part of a long distance relationship and can easily be a make or break factor! If you do not communicate, words can get mixed up and assumptions may be made. When you can't see each other, simply talk.
Long distance is hard. I am not giving these tips and saying if you follow this everything will be perfect, that's not the case. The case is though, if you trust your significant other, don't make assumptions, and communicate with them, the long distance can be easier. It's hard, but it's not impossible.