I don't know what's going on. I always dream that my boyfriend is cheating, or that I am with someone else and can't sleep well.

Your heart is so worried that you are always afraid that your boyfriend will get along with others and dump himself. The reason for this may be that you have no confidence in yourself, or in your boyfriend, or there are some problems between you that have not been solved, which makes you worry and becomes the fuse of breaking up, so you don't even feel at ease to sleep. I suggest you have more confidence in yourself and your boyfriend and try to solve the problems between you. Communication is the most direct and effective way to solve these problems, so I hope you can get along well with your boyfriend. Sometimes being too suspicious can cause unnecessary harm.