Complex sentence: Now that Derek has the ring, he just needs to find the right way to propose to Meredith, but is worried that she is not ready for marriage, he soon realizes she is when she makes a comment about having his children.
Split into simpler sentences: Now that Derek has the ring, he just needs to find the right way to propose to Meredith, but is worried that she is not ready for marriage. He soon realizes that she is when she makes a comment about having his children.