I had a relationship with God once. It didn't end well.
The problem with God is that He is stubborn. He is unwilling to really listen and he is either unwilling or unable to change. We started to disagree about what our relationship meant, he thought he was meeting my needs... but I didn't feel he was there when I really needed Him. Again, he was unwilling to listen.
We started to drift away when I changed and He didn't. It was awkward for a while, and then I left.
I haven't regretted it.