How to know when the interest is gone

I (24/F) have been manifesting this guy (23/M), made the first move and for the past almost two weeks we have finally been conversing with deep convos. he would reply a good amount per day as we are both busy, but the last three days he’s been replying almost after 18 hours. I think there was a drop of momentum on the conversations that went to the casual route, but now i’m overthinking and paranoid. Plus, I have seen him like posts within the time I wait for his responses. I’m not sure if this means this will fizzle out and if he’s disinterested?