Should I block him?

I knew this guy before he met my cousin. He asked for my Instagram when I was working at my old job, and I thought he was cute. He invited me to see a race with him, but I never went. However, since then, he has been consistently liking and commenting on all of my posts. It's a bit strange because he has a girlfriend who happens to be my cousin. I genuinely love their relationship, but his behavior towards me feels odd. He often glances at me, and he doesn't seem to like her posts as much as he likes mine. It's even gotten to the point where he would like my posts within a minute of me posting them. Maybe I'm overthinking this, but I'm afraid to bring this up to my cousin.

Should I block him?
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