Married But Lonely

Hello, all.

I am new to this page. I have been married for 4 years now and I am as lonely as ever. My husband and I are more like roommates, rather than a married couple. I feel like we have nothing in common, he is very grumpy and unhappy most of the time. Everytime I want to leave, he promises things will change and they never do. I know I could be a happy person but instead I just absorb all his negativity and act the same. I don't know what to do. Is anyone else stuck in a situation like this?