It may have nothing to do with you. Don't think it is because of how your body looks. If someone thinks about that, it would be a superficial relationship based only on sexual attraction. When people fall in love, the "in love stage" wears off. Then they are maturing as a couple.
It is possible that he is emotionally n
not ready for a big change. It may have felt easier/safer to talk about it but when actions were required, he's gotten cold feet. It may be also an issue related to his own sexual inadequacy. This is only a speculation. Let's say he has ED or low libido, etc. he's projecting that onto you instead of admitting what the issue is.
When you poured your heart to him, he may have felt overwhelmed feeling that things are moving way too fast. Only he can elaborate as far as what is going on in his head. If he is honest, whatever had caused this reaction in him, he should be able to let you know.
Something else to think about is whether or not there are others in his life ex, family, friends, etc who may be influencing him.