Why do I feel different about him?(5 star best answer!)?

My boyfriend and I have been going out for two wks now and I feel like I don’t like him anymore. Before we would say hi and smile and flirt but now..in p.e. we’re partners all the time and we just sit there and don’t say anything, i mean sometimes yeah but after it goes straight to silence. I know my boyfriend is shy around me and stuff but how can we smile more, talk,laugh and be FLIRTY!