How can I stop caring about what he does so much?

So i've been in this relationship for more than a year now, and now my boyfriend has changed so much i cant believe he's the same guy i fell in love with. at the beginning he was so sweet and thoughtful. now we are both in medical school, and even though i realize we both have to make some sacrifices and compromises, sometimes i feel like he just wants us to act like the relationship doesn't exist. a simple thing like a text or message in the morning, a good night wish... seem like too much for him. i know i am the kind of person that can't help but care a lot for someone i feel for. i made it clear that i don't want that level of care from him... but still it's like he just doesn't want to show it. for him, once he has love in his heart, there should be no need to show it so much. he has picked up this habit of walking away and going home while i'm angry or upset with him. i have told him over and over again how much it hurts when he does that, but he keeps doing it. just leaving me in school while im crying and heading home. and now, if i bring up the topic of feeling uncared, he just says its because i want to feel that way, and then he just leaves. if we're chatting, he logs out. if we're texting, he just stops replying. i ask him if he still loves me, he insists he does and wants to be with me. according to him, im just too sensitive and over-caring. so how do i stop caring so much?