The Book of Love

The Book of Love is a quest that begins in the Temple of Mara in the city of Riften. It is given to the Dragonborn by Danya Balu, one of the priestesses, when asking for the Blessing of Mara. To earn the Goddess of Love's favor, Danya sends you to the village of Ivarstead to help a local girl with a love problem.

Riften
This quest is easily located by entering the town of Riften and following the path on the left towards Mistveil Keep. The Temple of Mara is clearly marked by a pair of guards standing before an opening in the stone wall with twin banners hanging behind them. Enter the Temple and speak with Danya Balu, the Head Priestess of the Temple, and request Mara's Blessing. She will say that you must prove yourself worthy of the blessing by advancing the cause of love throughout Skyrim, and relays a vision sent to her by the Goddess to visit a small village called Ivarstead to the west of Riften. Head west to Ivarstead.

Ivarstead
Arriving at the hamlet of Ivarstead, the quest prompts you to speak with a girl named Fastred, who is in something of a conundrum with her parents. Fastred fancies herself in love with a local man named Bassianus, but her parents disapprove of their choice to leave Ivarstead for Riften. After speaking with Fastred, speak with her mother and father as well. Speaking with the mother will yield that she does not, in fact, disapprove of Bassianus, and would allow the pair to elope while she took care of informing her husband. Speaking with Fastred's father will reveal that his daughter is a rather fickle young woman whose affections change frequently. He will tell you that, up until very recently, Fastred was infatuated with another local man by the name of Klimmek, and that he is concerned that Fastred will leave the rapidly shrinking village for good is she chooses to leave with Bassianus.

You are now presented with two choices. You can head to the local inn to inform Bassianus that Fastred's mother is willing to run interference so that he and his love interest can elope to Riften, or you can investigate Klimmek's past relationship with Fastred. Confronting Klimmek will result in the fisherman realizing that he must be assertive with his feelings for Fastred, and let her know that he wants to be with her. Speaking with Bassianus will result in Fastred and Bassianus eloping to Riften, never to return to Ivarstead. Choosing either will result in the quest advancing.

Next, return to Riften to learn that the Goddess requires you to travel far to the west, to the city of Markarth to stoke the flames of love in the heart of Calcelmo, the eccentric Dwemer researcher and court magician in Understone Keep.

Markarth
Calelmo is having some lady trouble. He's attracted to a woman named Faleen, who works in the keep, but has no idea how to speak with her. Fearing the possibilty of offending her in some way by bringing up the wrong subject, Calcelmo asks that you get advice from a friend of Faleen's by the name of Yngmar, who is reputed to be quite... successful with the local ladies. You can find the lady's man in the Treasury Hall at night, or in the Silverblood Inn by day. He will reveal that Faleen puts on a tough front, but has a weakness for poetry. It just so happens that Yngmar has a poem that he can tweak to be about Faleen... for a sum of 200 gold. Pay the piper and take the poem back to Understone Keep and speak with the lucky lady. After prompting Faleen to read "Calcelmo's" poem, she will give you a letter to deliver to the bumbling researcher. Head back to Calcelmo, give him the letter, and proceed to follow him and witness his stumbling confession. With your job in Markarth complete, return to the Temple of Mara for your next objective.

For your final task, Mara requests that you reunite two lovers who have lost one another beyond the pale of death.

Gjukar's Monument
Gjukar's Monument is pretty hard to miss. Travel south-southeast of Rorikstead to find the spirit of Ruki, looking for the body of her husband among the ruins. Speak with her and she will ask that you help her look for her husband's body. With no corpses present in the area, you will have to head northeast towards an open plain. You will find the spirit of Ruki's husband directly south of Greenspring Hollow. Speak with him and he will ask you to lead him back to Ruki. At this point, you can choose either to fast travel back to Gjukar's Monument, or take the scenic route. After reaching Ruki, the two dead lovers will speak briefly, and ascend towards the heavens as they pledge eternal love for one another.

Return to Riften and speak with Danya Balu to receive the Agent of Mara blessing (10% decrese of Restoration Spell costs) and complete the quest.