Why would my crush add me back on snapchat 3 months later? first of all he just recently broke up with his ex & he’s not active on snapchat?

Okay so he had been dating his ex for i think 1,5 years and they just recently broke up. Around the time they were dating i added him on snapchat, i think it was somewhere around may & June, but he didn’t add me back, which kinda made sense because 1. he had a girlfriend and 2. he barely uses snapchat/social media. He did follow me back on instagram though a while ago. We would also casually talk to each other at school, always greeting & he’s the one who starts the conversation, not me. Him & his girlfriend just recently broke up & suddenly he added me back on snapchat? i was kinda excited but at the same time confused, why would he suddenly add me back months later if he barely even uses the app, because I've checked and his snapscore doesn’t even change which means he doesn’t send nor receive any snaps. So i thought it’d be a good idea to send him a snap first, which i did, he immediately opened it , but he didn’t reply back. it wasn’t a snap directly towards him, but he could still have maybe answered something, I don't know? he does watch my stories too, so i dont know what’s going on? do i have to start a conversation? i also don’t get what the point is of adding me back months later if you barely even use the app? unless he obviously just saw it, but i doubt it
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update: i sent him a snap directly asking him how he was and he responded with “goodd, and you?” i started a conversation out of that by saying im not good lol and i explained why. It was about me having to take a corona test bc of my vacation, so we talked about that. But eventually he started replying slowly, i think he got busy or something, so i ignored his last message. this was two days ago and we haven't talked since. im hoping he’ll feel more comfortable now texting me first
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oh also, a guy friend of mine was at the gym with him 3 days ago and asked him how he was doing and my crush responded with “fucked up man, but i need to clear my head rn so we’ll talk another time about it” , but when i asked him he answered with “goodd” so im guessing he’s not comfortable about being open with me or he just much rather discusses these things in real life? either way, he’s not over the break up yet, even tho he’s the one who broke up...
Why would my crush add me back on snapchat 3 months later? first of all he just recently broke up with his ex & he’s not active on snapchat?
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