Read this interesting article Opposite sex friendships: Is it possible?. I suppose the article is referring to special friend(s) as opposed to casual friends. So essentially, if your relationship with your spouse is good and with some ground rules, it certainly is possible. But if your relationship is bad or there are no ground rules, it may not be possible, it may worsen your relationship with your spouse, or may even be the reason for your bad relationship in the first place! Something to think about.