My peas flower beautifully and the whole plant is growing quickly and seemingly robustly but
David, If you are planting garden peas (not "Sweet Peas") it seems like your peas aren't getting pollinated. The ants are only there to get some sweet sap that occurs naturally. You could try planting some other plants around that attract bees, such as perennial salvias. If you have used garden insecticides, especially "Sevin" that kills bees, that could be affecting the pollination.