5'8" 285. 5", Size 4 and YOU'RE seducing him and he's not interested. Hmmm. Something is wrong here honey. You're instincts are correct. Take it from another husky guy. I don't know a guy like that who wouldn't be lovin life trying to keep up with you. hell, most would probably have a heart attack trying to keep up!

So, either he's gay OR, you found the other, slippery side of that coin. As a husky guy needing to get naked in front of a shapely young lady and perform, he may now be feeling self-conscience. Any chance you could have made a casual comment about his size or the attractiveness of another more in-shape guy? When you masturbate, do you use pictures of men who are in great shape?

Other than that, barring something like some infidelity on your part or something else that you might not be mentioning, he might have a medical issue like diabetes that could be causing a decrease in his libido.

Good luck!