Where did it go wrong?

Hello everyone I have been in a good relationship for the last 1 year and 11 months actually next month will be our 2 year anniversary. But of late things have been rocky if I may say. She has been moody and acting all weird. I travelled for treatment to india last month and even when undergoing treatment I didn't feel that love or the sense she cared as a partner. I was the one making the point to call and all that. So when i came back everything was okay till one day she fell asleep on the couch. I have difficulty sleeping so when I woke up in the middle of the night I tried waking her so that she could sleep in bed and all he'll broke loose. She became so moody,she talks to me when she feels like she just became different. God knows how much I care for her this is someone who also forgot about my birthday she didn't get me anything neither did she even tell me a simple happy birthday and we stay together. For the last few days I have been beating myself up asking what I did wrong to her. On God I have never raised my voice at her, or even thought of beating or harming her or even cheating on her.i practically do everything in the house she never pays for anything even when she has money. What wrong did I ever do to her for her to treat me this bad?