I need some relationship advice.

So, I’ve been with my boyfriend for 11 months now and he moved a few states away a few months ago and it has been an online relationship ever since. Ever since then, he started getting sad a lot and started doubting what he wanted. He’s constantly worried that I would cheat, he’s depressed nearly every day, but I know how he is when he isn’t like this. He’s a wonderful person with a big heart. Yes, I’ve talked to him about this and tried to make things better but it’s no use. I don’t want to break up with him.. he left and took several breaks on multiple occasions and he apologizes for how he is but he just gets back at it again saying “I don’t know what I want anymore.” “I probably can’t see you again for a few years” (I’m only 16) and sometimes he just regrets everything. It hurts me when he’s like this and he knows it, so it hurts him knowing he hurts me. The last time he saw me he gave me this ring that he payed for. It has my name and his engraved on it. It has real rubies and amethysts on it.. I know he’s true but he just worries so much.. my head is in knots 😖☹️