Mary and Rhoda Are Very Naive
I'm always stunned when I realize how trusting Mary and Rhoda are. Even for 1970s Minneapolis, they seem naive, especially around men they find attractive!
When the architect played by Bradford Dillman -- a total stranger -- shows up at Mary's door and says that he is drawing the house and wants to see the inside of her apartment -- she lets him in! She didn't even freak when he draws her telephone to get her telephone number!
IIRC, the "forest ranger" episode happens when Mary and Rhoda are at the auto shop and they let a total stranger -- the future forest ranger -- drive them home!
Mary apparently meets the "younger man" played by Peter Strauss at a supermarket and ends up spending the whole day with him. I would assume that they end up in a car together.
(If you think I'm obsessed about cars -- I just don't think it is wise to get into a car with a totally strange man -- or any stranger!)