Relationship problems

What do you think I should do. My partner and I have been dating for a few months. and he is younger than me. I am 18 and he is 17. His parents are very strict and sometimes I just wish he could stand up to his parents and tell them “today I’m going to spend time with my gf.” He has to ask permission to hang out with me. I don’t have to ask my parents permission to hang out with him my mom and Dad let me spend time with him when ever I want. His parents basically try to control his life. The way his parents are with him is really hurting me because I just wish he would know how to stand his ground but he always says that they’ll take his car away and he won’t be able to see me until he turns 18. I’ve stood up for him plenty of times every time my parents would comment something. I love him I really do. Any opinions on what I should do?