If the west stops sending the bullets what choice will they have?
If, as seems likely, there is no breakthrough before winter, it'll be another year or two or three of conflict. I'm not psychic, but I reckon the chances of the west continuing an indefinite support costing billions is zero.
BTW, the west has already ( apparently ) used up it's excess supply of munitions ( at least that's the reason Biden gave cluster bombs to Ukraine, isn't it? ) so that'll be the end.