My phone has the ring turned on and has vibrate activated. Yet I frequently miss calls on it. And then there are the times when it runs out of charge for half a day before I realise. Or I leave it in the car. Or I turn off the ringer because it would be intrusive (like in a workplace) and forget to turn it back on. Thankfully my friends and loved ones know how hopeless I am with my phone and don't take my missing calls personally.
That being said, perhaps you just annoy him and he ignores you on purpose. Given the amount of fights you have, it wouldn't surprise me if he was avoiding you.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.