John Gill Commentary Genesis 30:2

"And Jacob`s anger was kindled against Rachel: and he said, Am I in God`s stead, who hath withheld from thee the fruit of the womb?" — Genesis 30:2 (ASV)

And Jacob's anger was kindled against Rachel. Whom yet he dearly loved, hearing her talk in such an extravagant manner, as her words seemed to be, and were not: only expressive of great uneasiness and impatience, but implied what was not in the power of man to do.

And he said, [am] I in God's stead: Do you take me to be God, or one that has a dispensing power from him to do what otherwise no creature can do; and which also he never gives to any?

For, as the Targum of Jerusalem on (Genesis 30:22) says, this is one of the four keys which God delivers not to an angel or a seraph; even the key of barrenness. Children are the gift of God, and his only, and therefore he is to be sought unto for them: hence Onkelos and Jonathan paraphrase it; ``wherefore do you seek them of me? should you not seek them of the Lord?''

who has withheld from you the fruit of the womb? children, (Psalms 127:3); not Jacob, but the Lord.