Absolutely heart broken and confused

For the past 8 months I have been dating a guy that I am madly in love with. Up until recently we were the couple that everyone envied. Time and time again all I heard was what a special bond we shared and how warm our presence was. Clearly out loved could be seen and felt by those around us. About 3 weeks ago, my Father was diagnosed with advanced lung cancer and a brain tumor. Around the same time my boyfriend lost his job. Needless to say we are both under a great deal of stress. Two weeks ago I had knees surgery and my beloved took care of me day and night for 6 days. Over the past week something seems to have died in our relationship. For some reason he is no longer attracted to me and isn't sure if he is still in love with me. He says that he has no desire to have sex with me and that touching me and kissing me feels unnatural. He says he almost feels like a father or something. I'm not quite sure how this happened when it was just last Sunday we held each other and cried watching The Notebook. After the movie all he kept saying was how much he loved me. Now things seem hopeless. The other night he said that he is afraid to see me because of all the negativity in my life. He said he came over only because I don't have a choice with what is happening to my father and that it pains him to see me in so much pain. When I tried to kiss him I felt him tense up. I begged him to tell me what he wanted and all he could do was cry and say he doesn't know what's wrong with him that he feels so lost. I told him to just kiss me, pretend I was someone else if he wanted. His answer was I can't do that because there is no one else I want to kiss. It was an awful night and all I did was cry. I told him that maybe it would be best that the next time we see each other we spend time on us and not talking about his job loss or my father's illness. So last night we decided to have a date night. with no sleepover. It was so awkward which is so unusual for us because normally we can't keep our hands off one another and live in a constant state of bliss. At the end of the night I said I wanted to kiss him and he said let's just go home. When we pulled up to my place I tried to talk to him about what was going on with him and whether or not he felt he could be in love with me again. He said he was lost, confused and exhausted and suggested that we talk today. I am in so much pain over this. It's bad enough I am going to lose my father now I am going to lose the only other man in my life that I love. Is it possible that my boyfriend is in some sort of depression? I don't understand how you fall out of love with someone so quickly. He says he has no interest in another women, at least that I could understand. But this...I can't understand it. Anyone out there have any insights they would like to share?