I have been using dating sites for a long time. How to figure out if the guy is serious about me or is just looking for lust?

I met a guy in the past and we really liked each other's company but he always seems confused about our relationship. It was more than friends with benefits.

He never opened up & spoken about his thoughts

I have been using dating sites for a long time. How to figure out if the guy is serious about me or is just looking for lust?
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