Sounds like deer stripping. The leaves will likely grow back and plants still give a crop of beans. This happens to my pole beans every year. Here the deer mostly eat the leaves that are at their height plus the beans are behind a fence so they don't eat the lower leaves or the ones inside the fence though occasionally they will jump over this three foot high fence and eat leaves on both side of the bean trellis. They don't eat all the leaves just some. It does look odd with the vines and bare stems sticking out. They don't eat the beans.

Rabbits eat beans too. We do not have deers here, but the rabbits eat beans as soon as they come up. For the last few years I started my pole beans in pots and planted them in the ground when the stalks get tough, and stuck some dead branches around the base. This year, however, they even ate some of the stalks from the bottom. I have not figured out how to protect bush beans, other than fencing them in. Rabbits will strip the whole plants up, tough or not.

Rabbits eat our raspberry stalks to about 1" from the ground almost every winter. When they did, like last winter, we won't be getting much berries at all. Otherwise, we should have a good crop. I wish there is a good way to get rid of them.