If referring to relatives, spouses or partners, ask your source which term they prefer, such as “Joanne’s partner” or “Joanne’s husband”.
Do not assume either that a couple is married, or that a married couple want to be referred to as husband and wife.
Such preferences often become apparent in most interviews or conversations.
If in doubt, tactfully ask for a preferred term, just as you would ask a woman whether she wishes to be referred to as Ms, Miss, Mrs, Dr and so on.
It is better to avoid the term “de facto”.