Parents dont approve of living situation?

i am 22 and i moved in with my bf for the summer. I plan on moving back home at the end of august. I live with my parents as i am still in school and can not afford a flat on my own. My bf lives far far from me and I was offered a job by where he lives. I had been visiting him when I got the job offer. I decided to go for it and moved in. It was to be a temporary job. I informed my parents and they were happy. my job has since fell through and I am not unemployed, still living with the bf. I decided I would just stay for the summer since I already had made arrangements. My parents are furious and will not stop telling me to come home and how they dont approve. Mostly because we arent engaged. I feel like they are putting unnecessary pressure on our relationship and they need to back off. I am an adult and feel its isnt up to them but up to me. How can i get them to let go and let me do my own thing.