Help, please.

My boyfriend and I have been together for 3 months now. He does this thing where he will post on Snapchat but not reply to a recent text I send. But this isn’t just a brief time he will not reply for 8+ hours but continue to post. I’ve approached him on this and yet he still does it and it hurts me really deeply to where I will turn off my phone and MacBook so I don’t constantly check to see if he replied because I literally feel my heart sink and everyone knows that’s a terrible feeling. I’ve even taken the liberty to do the same thing to him and when I told him I did it to show him how I feel all he said was “ok” Should I be taking it personal? Should I approach him again? Is this a red flag? I don’t know what to do. I’m scared of seeing the “leave him” reply’s but at this point that’s probably what needs to happen...right?