Why does a guy won’t let go of me but is no longer consistent and put much effort?

I asked for clarity if there’s someone else, he has second thoughts, no longer wanna try… but he still says it’s none of that and claimed he’s just sick lately… he told me he still wants me, but he has just been distant and low effort ever since the time he came back after saying he needs time to think.
Why does a guy won’t let go of me but is no longer consistent and put much effort?
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