Why does he always do this!!!

Well this weekend we went to the fair and I always tell my husband we need to hold on to our daughter and never let go they’re only 3 and 2 especially in crowded areas, so this weekend he let our 2 year old go and I was paying for our food while my mom had our 3 year old I turn around and see my 2 year old next to a lady a few feet away from us and it was dark already! I was so so upset with my husband I always tell him not to let go of them they’re too small and he always tells me they’re be fine but no I don’t like that I don’t know how to make him understand we need to really watch our girls especially in crowed dark areas!!! He has done this a few times I’m so scared one day something can happen to my babies I don’t even like going out anymore and if I tell him let us take the double stroller or maybe we shouldn’t go he tells me why don’t you trust me I’m their father but when things like this happen it’s so hard to trust him, what should I do!?!?