I have to tell you I do not like this chapter of the Bible. It has nothing to do with some great theological dilemma, or even that I think Paul is wrong. The problem is that Paul is very right about something I would like to be different. There is an expectation I share with many that life should be easy, and when it is not we ask God to make it better and it happens. Big problem, that is not how it works.
We are never told what Paul's thorn is, but we know there is something which causes struggle for Paul, and he has put it before the Lord to clear things up. I would think when Paul asks God for something, the wish would be granted, much less when Paul pleads with God three times. This also makes me wonder about the statements in other places of Scripture that say we will receive what we ask for when we ask in the name of the Lord. So why didn't Paul have the thorn removed?
"My grace is sufficient for you, for my power is made perfect in weakness." (v.9) In other words, life is not going to be easy, pain free without struggle. What matters most is the work of God in our lives. I would love to have the answer be different, but it is not. We are called to faithfulness and trust, no where does this include a thorn free life.