Love, marriage, and pain connect in "The Yellow Wallpaper" in the main idea revealed in the short story: sexism.
Though the husband/doctor undoubtedly sees himself as supportive, he is condescending toward his wife/patient, and their marriage is the cause of the narrator's mental condition, not the cure.
At the root of the husband's enforced cure is the idea that mental activity is too strenuous for a woman. The men (the official physician is also male) insist on complete absence from mental activity. Doctors believed at the time the story was written that female mental illness was rooted in the uterus, and caused in part by too much mental activity.
I wouldn't say that the story presents specific revelations concerning love--it's not a philosphical treatment on the nature of love or anything like that. But it is certainly a comment on marriage, and the roles of men and women in marriage. And what the marriage results in is pain for the female. She is a creative, intelligent woman with a powerful imagination who is deprived of any mental stimulation. Her breakdown is the result.
The story is based on an actual cure Gilman herself was forced to suffer through and is a direct attack on the famous physician she was treated by.