I always assume nobody likes me?

Often you develop an opinion like that early in life. It can be from multiple sources, and events that happen in your life that confirm that belief about yourself, reinforce that view. Often events that would contradict that belief get dismissed by your brain. The ego likes control, and it likes a consistent view of self (even a negative one). Tara Brach might say that you believe in a small sense of self (because who you are really, is not just one thing).

perhaps any childhood abuse (verbal, physical, environmental) that make you feel like you were unimportant, less, or unworthy in any way. or maybe it is a mental disorder, like anxiety. there's lots of different kinds of anxiety and depression, maybe it's different from the kind you had as a teen. maybe depression is giving you an inferiority complex. maybe you're just insecure, or maybe you don't like yourself so you assume others don't. either way, i think this is a little bit common and you're not alone. my sister and i have both struggled with this. i think practicing self love and improvement as well as positivity and kindness will help the most :~)) hope this helps a little

Perhaps lack of self-esteem. You got to believe in yourself and remember we're all in this together, one little blue planet spinning around as a speck in the universe.