Feeling lonely, unhappy and dependent on other people

I’m not exactly sure why, but often when I’m alone I feel so dead inside. I wish I had a girlfriend again so I didn’t have to sleep alone. When I’m in bed trying to sleep I just have to put on a YouTube video or a twitch stream, otherwise I feel so lonely and I keep myself awake, for hours sometimes, with my own thoughts. I keep telling myself that I need to learn to be happy on my own, but I keep feeling unhappy when I’m alone idk why. I do have friends and when I’m with them I feel okay I guess, but as soon as they leave, I start feeling sad on my own. Maybe I’m just being a little bitch though.