Why is marriage so hard

On top of all the other issues we have, this one is the worst for me. I cannot touch my husband at night time at all. If I even put my hand in his arm he gets mad and pushes my hand away. He literally sleeps on the other edge of the bed nowhere near me. Things have been like this for about a year. I dont expect him to cuddle all night or anything but we dont cuddle. Ever. We barely have sex once a month. I feel so unwanted and unloved. We have been together for 3 years and married for one. Is this what marriage is supposed to feel like? To me sleeping together was always so important but now at night sometimes I just want to cry. I dont even feel married half of the time it feels like I'm single but someone pays the bills and makes dinner now and then. What am I doing wrong?