I'm a 22-year-old man and I'm feeling really unhappy in my relationship with my 25-year-old girlfriend. Does anyone have any advice?

I've been with my girlfriend for about a year and a half, having met her through my cousin. The first few months were amazing, but after that, I've noticed some troubling behavior from her. At first, her outbursts were not directed at me, and while I thought they were overreactions, I justified them given the circumstances. However, she slowly began to show her harsh side towards me. Our first major argument left me mentally exhausted, and I ended up apologizing in an attempt to move past it. Around the nine-month mark, I found an apartment suitable for both of us and invited her to join me. Shortly after moving in, her behavior worsened significantly—she would often yell or ignore me after work. Despite this, there were still moments when I saw her softer side when she was more relaxed. After a week or two, I reached my breaking point and confronted her, which led to another argument. Lately, her demeanor has become increasingly mean, although she still maintains a pleasant facade around friends, except for one incident when she lashed out at me in private. I've ended up sleeping on the couch more often than in our bed, and I find myself dreading returning home from work. My happiness in the relationship has diminished, but I'm too afraid to end things. I'm not worried about physical abuse, but I feel it's easier to endure her harshness than face the prospect of being single again. I'm hesitant to admit to anyone that I'm in a situation where I'm being mistreated, and the idea of explaining a breakup fills me with dread. A close friend of mine noticed that I seemed off when I visited him last Sunday. He texted to ask what was wrong, but I brushed it off, claiming I was just tired from working overtime. I'm scared of being single and feeling inadequate in relationships, leaving me conflicted about what I truly want in life. What should I do?