I would think that if one spouse actually had this disorder AND if the disorder had been diagnosed by a professional, that same professional could offer ideas to both partners as far as living with it went. In an a marriage that's otherwise what it's supposed to be most people (I don't think) would be unwilling to let a diagnosed (again, by a professional) psychiatric disorder ruin the otherwise good relationship. I suppose if it were extreme enough, and if the person wasn't willing/able to be helped by a professional it could erode at the relationship.
Having said that ,though, I think (no, KNOW) that people need to be extremely cautious about thinking some else has OCD when - really - it's often a matter of one person being "messy", the other one being "a neatnik" (but without OCD at all), one thinking the other one is unwilling/unable to remain neat and organized, and the other one thinking his spouse has OCD.
A lot of "messier" people can't believe that someone could be a neatnik without having OCD. They don't understand how effortless being neat and organized is for some people and/or they don't understand that some people function best when things are neat and organized.
Unless a messy person is extremely, extremely, ridiculously messy; most neatniks generally understand that not everyone is as much a neatnik as they are. Many neatniks kind of assume, too, that messier people just don't find being neat as effortless as they do but don't assume the messier person has a mental disorder.
Of course, for every neatnik who is more understanding of individual differences there are others who jump to the conclusion that their messier counterparts have the disorder of hoarding (and if not that, then "maybe ADHD").
Some messy people (or at least messy-side) people don't seem to be able to function very well if they have to "worry about being neat and organized". Maybe because being neat and organized isn't a priority, and doesn't come naturally, to some messier people; they, on the other hand, do often seem less "generous" when it comes to assuming that those who are different from them have a mental health condition.
So my answer here is that someone has to ask if the neatness is stopping a person from functioning normally in his day-to-day life. If it is he should get help, and the spouse should consider asking for advice on how to be supportive as well. Messy or neatnik, people are sometimes just different and yet perfectly mentally healthy.