Boyfriend is depressed

My boyfriend and i have almost been together for two years. We spoke today and he for the first time came to a conclusion that he may be depressed. When i met him he was so care-free and for the longest time i assumed he was so emotionally intelligent. He seemed like the least bothered person on this planet (i swear). He just was always so happy and made jokes and within the past year that slowly disappeared. He isnt confident anymore and all of that. Im afraid i played a part because i went through something and may have made him my saftey blanket at times. But i dont think that could have been the whole reason... i have never had to deal with this before and i was wondering what i should do to help him. He has left to go back home for winter break and i did a nice deed and cleaned his whole apartment because ... it was a mess. At first i thougjt it was just laziness but the more i cleaned it seemed like a depressive episode tbh, it made my heart hurt. And hearing him own up to it today has made me feel very lost because he said only he himself can change how he feels (very true). However i just want to make him happier and i want him to know he always has a safe space with me. Any help ladies?