Michelle,
I read your friends problem and it could be many different things.
It could be physical, such as a seizer. I don't think it has anything to
do with unforgiveness.
It could be something from his past that is still haunting  him.
Such as some kind of involvement with the occult.
Does he own any idol from some other religion? If he does, then
he needs to get rid of it.
Maybe their is a curse that has been in his family, and this is a
continuation of that.
You said that is seems to involve a Christian lady.
Are you sure she is a true "Christian " lady?
Some Satanists infiltrate churches unknowingly to other
members of the congregation. They seem like wonderful
Christians, and lead many astray. A wolf in sheep's clothing.
 
If she was a Satanist, then she may have put a curse upon him.
He needs to find someone who is knowledgeable about these things.
Have him to anoint himself and everything in his house with Olive Oil,
and Plead the blood of Jesus over everything.
Their is power in the blood.
Renounce any involvement with the devil.
He must do a thorough purging of his soul. Past and present.
Have him to put on the whole armor of God everyday. All he has
to do is ask God to do this.
Find people who are full gospel, and have them to lay hands on him
and to pray over him.
Pray to have the Angels surrounding him.
Pray, pray, pray.
Demons are very real, and they do have limited powers.
Once they come into your life , they are hard to get rid of.
It takes time and perseverance.
 
Susan