All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
It is forbidden to sell pork or drink. If your husband's friend sells wine and pork besides other lawful stuff in his restaurant then his earning is mixed with forbidden money. In this case, dealing with such person is allowed since the Prophet used to deal with Jews whose money was mixed with forbidden money. See our Fataawa 84460 and 86619.
So, it is allowed for your husband to have partnership with him only in lawful business that is free from forbidden activities.
For details read to Fatwa 90112.
However, the fact remains that it is preferable for your husband to choose a pious partner to have their commerce blessed by Allaah.
Allaah Knows best.