by Mr Thick
What did Derrick put into his wife's drink?
It is not credible that she would start as someone who thought sex once every eight weeks was about right to someone who spontanteously wanted to have sex with her husband's friend in front of her husband and the wife of the man she was attacking.
It would be a little more credible if she had started to be affectionate with her husband, tried to get him into a more private place, and then attached him anyway when he did not want to leave.
Sharing in this way might lead to swapping or swinging later.