Is my boyfriend cheating on me?

Lately iv been havin this feeling around my bf.i feel like were bffs but i used to miss him all the time and now i dont?weve been datng 8months and its not really makin sense ne more. then my friend texs me last night sayin him and his friend were at mcdonalds with 2girls sittin boy girl n he seemed surprised my friend walked in there.i tried seein the positive of maybe his friend jus was tryin 2get some and draged him along?i havent answered his calls aand dont really wana tlk 2him right now...is he cheating and what should i do?