Why am i being ignored?

I have dated this guy for almost 3 years. I hav noticed he has been pulling further away from me. I usually stay at his house but lately he hasnt been coming home till 6:30 in the morning. I noticed his car at a close bar to my grandmas home last night so i went in. He promised me he would be home and tht he would tlk to me after he dropped his friend off. However he didnt come home until after 5 that night. i wrote him a note telling him how i felt and left it on his bed but he made fun of me by texting me "nice poem leonardo" he tried calling but i was sleeping. Its been longer than 24 hours since ive heard from him wht do u think i should do?