How to Stop Worrying About a Guy I Really Like?

How do I stop imagining the worst case scenario? There's a guy I really like that I almost dated, but we have to be long distance for about three months, so we decided it's best to be friends and revisit dating when we see each other again. First month and a half went by and we texted nearly every day. However, suddenly, he's stopped responding. It's been over a week, he NEVER doesn't respond. I don't think anything is wrong between us because he's really good at communicating when he's upset and would tell me if he needed space or whatever. He also hasn't been active on Discord, and he's almost always on there. I was thinking maybe he went on vacation, but I figured he'd tell me "hey I won't reply for a couple weeks because no internet where I'm going." I'm really starting to get worried about him. How do I stop myself from worrying? I feel like something is really wrong, but I have no way of finding out until he replies again. I have his roommate's number, but he asked me to never text his roommate unless there's an emergency, and I don't know if this counts because he actually could just be on a trip he forgot to tell me about (he has SEVERE ADHD, so that kinda happens, just not usually for this long tho).