Boyfriend going down on me

So I’m having this probably and I don’t feel like I can help it, and it really sucks. When he started going down on me it didn’t take much longer then like 10 minutes for him to get me off while going down on me because he knows just sex won’t do it. But now I try to minimize how often he goes down on me because i know he gets discouraged when he doesn’t get me off (which was only once because I have been faking the rest) and he gets really tired really fast because the only time we have to do it is in the car after practice. So every time he asks I try to be like “I wanna go down on you first” and then take up most the time and then we fuck, and it feels really good if just doesn’t last long enough to actually get me off. Past few times he has gone down on me after 5 or 6 minutes I just fake an orgasm so it makes him feel better and then just pretend to be sensitive so he doesn’t like feel me down there because after that I’m not horny anymore because I hate faking it, but I do it to make him happy. Should I tell him that I faked it or should I just stop faking it and hopefully soon I do get off? Honestly anything would be nice to know....