Most Helpful Guy
Yes it's an insult the terrible "nothing serious". If I were you I'd say "ok, then let's move your ass to a friendzone and look for someone serious".
Most Helpful Girl
When a guy says he doesn't want anything serious, believe him.
he's just in it for "fun"
He doesn't want a long term relationship right now
If you want a relationship, move on.
You will find another guy