Is it ridiculous to wait for my boyfriend?

Hes going to be gone for 4 years after marines boot camp and I told him I would wait for him he said that if I did it wouldn’t be fair and to first get my life going then come to look for him… I don’t mind waiting for him as I encourage everything he is doing even though I know ill miss his to death I will keep myself busy and as he said get my life started I will not cheat on him AT ALL I love him more than anything… Do YOU think its crazy to wait for your gf/bf for this long? Would YOU ever do it, if youre so inlove with the person? Could you handle it? This question wont change my thoughts but just want to know what others think and their reasons .