The Two Worlds of Jennie Logan
(1979)

Lindsay Wagner played Jennie. She left her husband after she found out he had had an affair. She went into the attic of an old house and found a white Victorian dress, which she tried on. She became dizzy, passed out, and when she awoke discovered she was in the 1800's.

She met an artist, played by Marc Singer. Throughout the movie, she kept going back and forth through time (after realizing that every time she wore the dress she did so), trying to figure her life out, deciding whether she wanted to stay with her husband; and falling in love with the artist. She attempts to tell her husband about her "travels" but he doesn't really believe her, and wants her to come back to him.

At the end of the film, we see her husband enter the house and look for her. He finally winds up in the attic, and starts rummaging through some things. He comes across a painting from the 1800's, (which the artist had painted), and is of her, the artist, and their two children. He then realizes that she stayed where she wanted to, which was in the past with the artist.

Thanks JoAnne!