Ruining the relationship..

Im in a pretty good relationship thats lasted 4 years but i cant help but think about couple things differently than whats expected. I dont want to get married because of how complicated divorces can be despite him just waiting on my go ahead to start things rolling for a proposal. And im scared to have any kids with him because i wouldnt be able to raise my child alone at this stage in my life, despite him wanting a family and wanting to raise children with me in the next couple years. Im a very pessimistic person and even though i havent been diagnosed or evaluated im pretty sure i have severe depression. I cant tell if its my pessimism and depression causing this or that its a terrible relationship?