My boyfriend dosent seem to want to have any type of intimacy with me

My boyfriend and I have been together for 3 years and a half and its been amazing. Till a year ago we used to make-out and get horny with each other all the time but the excitement has gone down. Im very affectionate and love giving kisses and hugs and even getting a little crazy in public. He used to be like this with me all the time and it was always very exciting. Now he will only kiss me when he first sees me and kisses be goodbye, and only with pecks. Maybe hell lock lips with me but only when i ask him to. When i try to kiss HIM and grab his face or make a move, he’ll put his mouth in peck position and basically wont let me give him a nice kiss or even lock lips. Its very frustrating and I’ve confronted him about it several times. When i say “i want to kiss you so bad right now” hell say “yea, me too but we cant right now”. Im a senior in high school and his parents are super strict so we very rarely have time alone so its kind of hard to find real privacy. Also, sometimes I touch around his areas or thighs just to tease him a little to see if hell make a move but he just gets mad or seem uncomfortable. Ive also shown him my desire to have sex and he just puts excuses not to (we have had sex before). This is very unlike him, he used to show interest in being intimate and even request things from me but this has been happening for a year now and im kind of tired and worried. Also, when i do confront him or ask him why does he turn down my requests he says “Last time i asked for something you denied too and i wasnt asking questions or getting mad” and he has never asked me for anything in a really long time so he’s lying and making excuses to make me feel guilty about it. This makes me feel embarrassed to show if im feeling a little frisky or even show a lot of affection, Ive expressed all of this to him and he says he’ll try to change that but i dont see any change. What should I do???