It would be a good idea to get all the guys married off to the girls in the game. Of course you shouldn't marry off the girl that you want for yourself.
Here is a list of who will go with who.
1. Cliff and Ann
2. Grey and Popuri
3. Harris and Maria
4. Jeff and Elli
5. Kai and Karen
How do you get the guys to marry the girls? Simple. You have to befriend them. Each guy likes different things. Give them the kinds of items they enjoy most.
There will be scenes with all the couples once they start falling in love with each other. Eventually the guy will come to your farm and invite you to the wedding.
Here is where everyone will live once they're married.
Cliff and Ann - Green Ranch
Grey and Popuri - Green Ranch
Harris and Maria -The Mayor's house
Jeff and Elli - The bakery
Kai and Karen - The vineyard
Cliff likes all sorts of things. Berries, milk, flowers, and cake are good things to give him. Once you're his friend he'll start talking about betrayal a lot. There are a couple scenes with him and Ann. In one he arrives at your house to give you fish. He ends up bumping into Ann and knocking her over! They also argue in the mountains about Cliff's pet bird eating an animal.
Gray really likes eggs. Try giving him an egg every day and talking to him. He'll even give you a recipe. Gray does a lot of cute things to make Popuri like him, such as planting flowers at the Green Ranch.
He pretty much likes anything. He seems to like the Edible grass a lot though. Once you're his friend he'll start talking about connecting people together. In one scene Harris ends up saving Maria from Sammy the salesman. In another one she gives him a letter, and he blushes a really bright red and begins to sweat everywhere.
Jeff likes milk. You'll make him especially happy if you give him golden milk. Once you befriend him he'll start talking about tea and Elli.
He likes all different types of berries. Once you have become his friend he'll start talking about his past a lot. He also will talk about Karen and how kind she is to him and such. In one of their scenes together, Kai is trying to calm down Karen. She's extremely angry and leaves the bar. He follows her because he's really concerned.