SO Silents phone at night

My SO silents his phone at night, he says it because his family from the islands call him too early with the time difference and he gets off work at midnight an doesn't want broken sleep. Does anyone else silence their phones at night? We've had issues with infidelity in the past.. like his phone being on sleep mode an I turn it on to him getting good night messages about two years ago. He says that's in the past and when I ask him why is phone on silent he he gets defensive. But my phone can't be on silent or I'm doing something wrong. I don't suspect he's doing anything though anymore. Just hate that his phone is on silent at night..