Does it always feel this way?

The reason why I ask this question is because, I finally got to see one of my best and longest friends. I finally got to see them after about 2 years of being apart and, for some reason I felt happy and like this gap in me was filled and I was allowed to be myself. But, after like an hour or so I had to leave and say goodbye to my friend not knowing if I'll ever see them in person ever again. Now this hurt to leave them, it felt like I was lonely again and that I had just abandoned them. So my question is, does it always feel this bad to leave a friend not knowing if I'll ever see them again?