The David P. McWhirter, M.D., and Andrew M. Mattison, M.S.W., Ph.D. study reported in their 1984 work ''The Male Couple: How Relationships Develop'' stated that in regards to relationships involving male homosexuality that "all couples with a relationship lasting more than 5 years have incorporated some provision for outside sexual activity in their relationships."<ref>United Families International citing the book[http://www.unitedfamilies.org/documents/UFIfamilyIGSOfullpage_000.pdf ''The Male Couple: How Relationships Develop'' by David McWhirther and Andrew Mattison (Englewood Cliffs:Prentice-Hall, 1984), pages 252-253]</ref> | The David P. McWhirter, M.D., and Andrew M. Mattison, M.S.W., Ph.D. study reported in their 1984 work ''The Male Couple: How Relationships Develop'' stated that in regards to relationships involving male homosexuality that "all couples with a relationship lasting more than 5 years have incorporated some provision for outside sexual activity in their relationships."<ref>United Families International citing the book[http://www.unitedfamilies.org/documents/UFIfamilyIGSOfullpage_000.pdf ''The Male Couple: How Relationships Develop'' by David McWhirther and Andrew Mattison (Englewood Cliffs:Prentice-Hall, 1984), pages 252-253]</ref> |