IS MY BOYFRIEND CHEATING !!!?

I was on the phone with my boyfriend we usaully talk every night from 9- 3 at least but last night it was about 9:30 and he said he had to call me back it was 12 he neva called back I txt him saying gnite he said he's playing video games with his cuzin now i wanna belive him but i cnt. i need feeback !!!