OMG! i felt the EXACT same way a while ago! There was thing guy, who i was friends with and i knew he really liked me, but i didnt like him and nothing really happened. Then he started chasing after another girl after a few months. I felt sort of put out too, since i no longer had his attention all the time. And I went through thinking that i liked him too! So, its not just you
I'd just say to him in a jokey way, like : 'Hey, dont i normally sit by you on the coach? :P'
Like in a cheeky way? not serious? And see what he says.
Theres nothing to do if he's moved on, unless you do like him back! You should think hard what you say to hiim in a serious way though, dont want him to think that your playing him along, or anything.
Good luck

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