As you continue to see this fellow you will find out many things about yourselves that doesn't quite mesh, and may well become annoying to each other. I think its too soon in the process of learning how to talk and understand each other to be discouraged, but not to take note of the things you cannot, or should not change and after 3 month the sex may be great, but certainly not perfect.
If this is not an obstacle that can be overcome then what's the point in even thinking long term at this time. I mean who thinks long term after 3 months? That's not practical since this is supposed to be just the honeymoon any.
You are lucky because most ignore or never learn as much about the conflicts between couples until much later and already too late. You have recognized a sticking point and in all fairness should never commit to anything deeper than what it is now. Moving in is certainly premature and foolish because until his good points far outweigh the bad, seems he ain't that great as a long term partner any way.
Sexual incompatibility after 3 months has always made me cautious, and reluctant. Sometimes you have to quietly back off and see what happens without ultimatums, anger, or insult. I am a guy and I value honesty over ego, and if I wasn't open to satisfying my female the way she wants, what would be the point?
We can be friends but not an exclusive couple which is real simple. My advice is keep talking but don't give him not one extra day that he isn't worth, because people seldom change unless they want to. How do you think long term when short term isn't doable?
Red flag when they are not willing to explore and experiment unselfishly while they get their own rocks off. The next time he brings up the rather lame excuse of you not being able to orgasm so what's the point, make sure he understands why and screw his fragile ego. That would be the honest approach.
Good sex shouldn't be so hard should it? Never let a partner get away with short changing your needs without a better reason than he has given. Why make his problems and issues yours after just 3 months?
That's another red flag NOT to be ignored by the fantasy of his future potential.