I love to tell the tanabata story which I shape so it comes out as true love that lasts forever even though they can only meet once a year. Mine is a mix from many versions including Lafcadio Hearn - but I would start with googling "The Weaver Girl and The Cow Herd" if you want to look into it. Wikipedia is good for links to other sources.
I'm fond of a traditional Jewish/West Asian folktale about a clever young woman who solves several paradoxical riddles posed to her father by the local ruler. Impressed by her wisdom, the ruler marries the girl, first extracting a promise that she will not meddle in his affairs of state. She agrees, on the condition that if she ever displeases him to the point that he sends her back to her father, he will permit her to take with her whatever single object she treasures most. A time comes when the woman advises a poor man who has been cheated by a wealthy neighbor, thus enabling him to convince the ruler to reverse his own faulty judgement in the case. The embarrassed ruler recognizes the hand of his wife in the clever argument of the poor man, and angrily banishes her for violating her oath. She humbly agrees, asking only for a final supper together as husband and wife before she departs. During the meal the clever woman gets the ruler falling down drunk, and when at last he passes out she has him conveyed to her father's house along with her personal possessions. In the morning the confused ruler wakes in an unfamiliar dwelling, with his wife lying by his side. He demands to know where she has taken him, and why. She reminds him of his vow when they were betrothed. She has only taken her due -- the most precious item to her of everything in the palace -- her husband. Touched by her wit and devotion, the ruler is reconciled with his soul-mate, and they live many long years in loving affection.
Let me know if you want the source reference(s) to learn the details (the three riddles, the lawsuit of the poor man, etc.). Good luck with the wedding gig.
it's got european versions too - I first came across it as Catherine, Sly Country Lass in Calvino - am just putting a version together and picking and choosing which riddles and tests and dispute to be ruled on I am going to use - but the reason I love it/the versions I love are the ones that end with the "kidnap" of the king as a form of devotion.
I would suggest in the tradition that the teller tells the story of the couple. From childhood to when they met to the moment that is being witnessed. Ask the bride and groome their story. Then fashion it the way you would a love story. The kiss theory here. If this doesnt help hit me back and lets talk.
The Greek myth of Baucis and Philemon, found in Ovid's Metamorphoses, while not a romance, ends with an indelible image of the couple getting their wish: to never see the other die, and so they are transformed into trees, standing together forever: two distinct individuals, but whose branches and canopy intertwine, supporting each other.