Guy's Behavior

My ex added me again, what does this mean?

My ex of a year, we had deleted each other off of all social media and had no contact for over a month. Until one day I put my Snapchat username in my Instagram bio and a few hours later he added me. Bear in mind He wasn’t following me on Instagram so he would’ve had to go onto my profile with effort. I added him back and then he followed me on Instagram. He continued by liking my recent photos, however it’s been a week but he hasn’t actually said anything? I’m wondering whether this means something? Why all of a sudden he’d do this when he’s the one who ended things?
My ex added me again, what does this mean?
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