I was texting my girlfriend when her sister suddenly found out (her sister knew her password). Her sister told me not to look for her in the future. What should I do? What should I do?

It seems to have something to do with her sister, but it doesn't matter much in essence. You'd better find a girlfriend yourself. After all, feelings are what you and your girlfriend have to say. If you really like it, put down a man's self-esteem, say no to her sister and go straight home. Men. Don't complain. Take the initiative if you like, and put down your face if you like. If you like it, act quickly. I don't believe his sister won't be moved by you.