Is it that serious?

So last weekend my grandmother was in town and my Leo friend called me and I didnt get a chance to return his call.When I seen him in the gym mOnday he confronted me about not calling him back and I explained the situation. I didnt relaize it was so serious. Every since then he has been treating me different and it kind of has me down in the dumps. He has since mentioned me not answering TWO more times and hasnt been calling me as much. ANd it seems as though he has been doing things to purposefully make me jealous..I dont know what to do. ):

tell him to knock it off. he's a leo and can handle u being direct with him. call him on his shit. we respect that. after you've put him in his place show your affectionate side. pal around with him and let him know that u do not do these things with the intent to hurt him but ur just the type to not always answer their phone. stand firm and don't be swayed by his ego tantrum. he'll know he has the upper hand if u react to him emotionally. become a little more aloof and detached and show that it's not gonna work on u. he'll eventaully come to his senses and back down. if, or when, he apologizes then reassure him with some affection.

Thanks. I guess I kinda lost it on him already. I told him I basically didnt like what he had been doing...and he acted oblivious. I told him he was insensitive and his reply was "OH I'm being insensitive..I understand your granmother was in town but YADA YADA. YADA".....And I just dont get the HUGE deal I guess. I think he mightve thought I was with someone for the weekend. But I told him I didnt like how he was acting so I choose not to deal with it.