Tears make most people feel helpless and they want it to stop, to comfort the person who's crying or even walk away.

I'm sure the more you talk to him about how you feel and what the tears mean to you, he'll get used to this and learn to love the gift you give to him. If he's never been good at dealing with this, it might take a while to get over the reflex to slow down, but he'll get there. I've been a bit like that most of my life until I started working with patients and learned that a lot of the time, their tears were a huge step forward for them - it was a good thing. What a revelation, lol.

I'd second what Ozme said...establish a safeword to give him a tool to know where you stand emotionally and physically. He's still learning to 'read' you and this might give him the safety to move forwards.

And yeah, I've never cried in front of anyone else - he's broken that spell. Even a simple 'I love you' can make me cry sometimes, not only because of his feelings, but also because I realise that I'm allowing myself to feel that way, too, and share it with him. Those are happy tears...*smiles*