I have to agree with the others. You may not be forcing him, but you are confusing him with your body language and the general set up of the whole situation.
Lunging over single fences higher than two feet can be dangerous in a circle that small. You're asking him to perform a turn into a jump that he is simply not physically capable of doing - it is better fit for an amateur stadium course.
The jump is not set up correctly - see how deep he is getting in to it? That's because he can't see how high or far away it is. It has no ground line, or even a second pole to give it any depth. See this post
for more detail on how horses see fences.
My suggestion? Free-jumping him (correctly) to assess potential is great. Try setting up a chute (made of poles or even simple flag-tape) with a properly strided and set up grid, and you'll get better results. It allows them to set themselves up with little or no human interference (except for the intial "go on" shooing at the beginning), they can go in a straight line, and grids naturally help horses (and riders) to get a good rhythem and settle into a nice jump.
Here's an example
of free-jumping a grid.
And remember - absolutely do not over jump him! Notice that I said to assess potential
, not to train
. He's three and he has plenty of growing to do still, and you'll want him to have a long and happy career by remaining nice and sound. ~