Borrowed Blonde(1947)

Leon's boss and his wife aren't getting along together, so Leon asks them to visit his home and observe how he and Mrs. Errol manage to keep the old knot tied. Before the couple arrives, Leon manages to get into a situation with a pretty, blonde neighbor, which leaves him having to introduce her as his wife when they do arrive. Neither Leon's wife, when she comes home, nor the neighbor's husband are too pleased with this arrangement.