It is never a bad idea to make an effort to see that one’s spouse has an involvement in every friendship. My husband and I have lunch dates alone with our friends, including priests, sisters, and friends of the opposite sex, but both spouses always know, both spouses may always veto on the grounds that they are not comfortable, we make an effort that gatherings with both spouses present do happen from time to time, and it is always understood that the other spouse is always welcome to join, even with no advance notice, if it becomes possible. There are couples who are even more cautious than that, choosing to do without even public one-on-one meetings with friends of the opposite sex, and I don’t see them as necessarily being excessive.
Differences in interests are a different matter, but I don’t even like to have women friends that make my husband uncomfortable. Sometimes a spouse senses unhealthy aspects in a friendship that are invisible to the friends themselves. That should never be ignored. (It goes without saying, of course, that if you can’t find friends that your spouse will approve of, you’ve got some problems of another sort!)
Excepting what routinely takes place in the confessional, any relationship that doesn’t admit the spouse is almost by definition a therapeutic relationship, and has to be conducted under professional restrictions. Actually, I even put some formality into a pastoral relationship that I wouldn’t necessary do with a priest that we as a couple only see socially, because of the closeness of the confessor/penitent relationship.