My boyfriend doesn’t want me going to the gym?

a few weeks ago I Told my boyfriend I’m about to go to the gym and get a trainer I gained 15 pounds last year and wanted to lose the weight before the summer time he told me he didn’t want to go because all guys ever do is go to the gym and try to find someone to sleep with especially trainers but yesterday he told me he was about to start going to the gym with his brother and told me he would help me at home to lose the 15 pounds I want to lose is that weird? Guys try to talk to me when I go outside anyway so what’s the difference
My boyfriend doesn’t want me going to the gym?
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