Pedigree Forge supports same-sex couples and does not usually distinguish between "husband" and "wife". These terms are used mainly for chart placement: traditionally, the husband is placed to the left of the wife, or flanked by wives when there are multiple marriages.
When a couple is created, the male is set as the "husband" and the female as the "wife" by default. If no sex has been assigned, the first person added is the "husband" and the other the "wife". Think of these as "Partner 1" and "Partner 2" — the labels control positioning, not identity.
To swap the roles for a couple, ensure one member is the active person and the other is the selected spouse, then use Edit > Spouses > Swap roles.
Note — These roles are also used when importing and exporting GEDCOM files, where the "husband" maps to the HUSB tag and the "wife" to the WIFE tag.