Any Rav who is well versed in inyanei Shalom Bayis will never say that one has to honor parents before a spouse. However, having said that, as I have mentioned before, it is best that couples as a team honor both sets of parents together.
It is customary to serve parents (as they are also older) first at the table. However, my father and mother a”h always complained and told me to serve my husband first, while my husband insisted that I serve them first. When his parents were at my table or when I helped serve at their table I always served his parents first. Obviously I am not speaking about serving food. I am speaking about when there is an issue, the spouse comes first before the parents. However, if you work together as a couple to honor and respect both sets of parents you probably won’t have too many issues where this problem will arise.