God doesn't understand our feelings just because he made us. He understands them because he felt them himself.
God saw it fit to become human himself. He laughed, he cried. Jesus was funny. He told several jokes that we can read in the gospels. He was a funny guy.
Jesus had a mom. He called her "mom" (in Aramaic, of course). He helped his Pop with whatever odd jobs Joseph needed. He had chores.
I'm sure Jesus wanted to go out with friends on the weekends and Mary wouldn't let him. He was human. This is something we tend to lose sight of. Yes, he was fully God, but Jesus was also completely human.
There were foods he liked, and some he didn't. He felt pain, joy, and sorrow. He felt love. He was probably a morning person, but I don't know - he may have liked the night-life better.
Jesus understands us because he lived like we do. We don't have to rely on God to understand our feelings simply based on the fact that he created us (although that is a good reason). But moreover, Jesus knows us and how we react because he was human as well.