I totally agree as well. It is shocking that he hasn't forked out the money when he can obviously afford it and is as good as being her husband. I'm sick of hearing about actors and celebs declaring themselves bankrupt to get out of paying their bills when they are living in luxury compared to the rest of us.
Why should he pay. As an unmarried couple they get none of the financial benefits to being married such as the removal of CGT between each other. So why should he cover her debts?
In fact, since they are unmarried, any gift he gave her to pay off her tax bill would probably be subject to CGT meaning he would be paying an additional 28% to clear her debt.