The play Double Solitaire was originally presented alongside a play called Solitaire in a Robert Anderson double bill. Reportedly some couples left the theater and headed for the nearest divorce lawyer. Others had sincere conversations and reflected together more deeply than ever. Robert Anderson wrote quite a few plays about marriage but his most famous films largely focus on other things.
The film's title should give you a pretty good idea of its main theme; quietly desperate marriage defined by isolation and slow disappointment. The source material is strong, crystalizing common but haunting issues with generations of couples.
The adaptation is minimal. The sets are basic. The acting is basic. The cinematography is barely noticeable. The score is a bit dated.
If you are a fan of psychological realism or Robert Anderson, in particular, this movie is definitely worth checking out although I suspect it is somewhat worse than just seeing the play.