He had intercourse with his wife when she was observing a voluntary fast

No File Exists
Check below answers in case you are looking for other related questions:
He started to observe a naafil (supererogatory) fast then he was invited to eat and he ate
Should she ask for a divorce from her husband who does not pray regularly and does not give her her rights?

No File Exists
Related Answers:
I want us to get our own place but my husband refuses; what should I do?
Is it permissible for a wife to give up her share of inheritance without her husband’s permission?
If a married son does not live with his mother, is he regarded as being disobedient towards her?
He started to observe a naafil (supererogatory) fast then he was invited to eat and he ate
Should she ask for a divorce from her husband who does not pray regularly and does not give her her rights?

Recommended answers for you:
The reason why smoking is haraam
Problem between a daughter and her mother
Conditions of women going out to the mosque
The reason behind ‘aqeeqah
Jamaa’at al-Tableegh – pros and cons