Q: While fasting how much distance should a husband maintain from his wife?
A: This depends on your self restraint and control. If romancing lightly with the wife does not affect you and there is complete control then it is fine.
On the other hand, if you feel that you will lose control or get carried away, then do not do so.
It will be best not to do anything while fasting.
Allah Ta'aala knows best.
Moulana Yusuf Laher