Why does this guy do this? what should i do?

i REALLYYY like this guy. but he confuses me. he says hello sometimes and it seems like he wants me to talk to him [but it might just be me] okay and other times its like im not EVEN THERE! and he just looks really mad sumtimes. but then i see him with his frends and hes just DANDY? but this one time he held the door for me :] nobody does that! so i was just really surprized, but maybe hes just a gentleman.. yeahh. his eyes are soo brighttt. idk.. we barely talk.. WHHYYYY??? why does he say hi if he cant even have a conversation with me! why why why? im so confused. also he might think i have a boyfrend. cuz i have this reallyly close guy frend and evrytime hes around i just so happen to be walking with him and stuff.. one time he even sayd hello to me and walked RIGHT in between us. haha. my frend was like '..' but hes nice! idk. should i give up? ive liked him for soooooo long... what should i do? i become a mindless zombie or sumthing when hes around. not to mention EXTREMMLYYY CLUMSY.