If you win an expert festival while married to Katie, this dialogue occurs:
Congratulations on coming out victorious. What? You want a tangible reward for your behavior? Hm, that's true. I've observed how hard you've worked, after all. Fine. What would you like? ...WHAT?! Th-That's... No, uh... Well, I... Yeah, I got it. No need to elaborate. I'll take it under advisement.
If you try to milk a bull in A Wonderful Life, instead of being annoyed (or nothing happening), it responds with a green heart. To make it more obvious, if he is too young to breed he will be confused.
The "Miracle Portion" in Japan isn't a potion. This game makes it obvious. When you decide to use a "Miracle Potion" a cutscene occurs wherein you are advised to leave the barn (despite being an adult), followed by a sound of loud mooing. The next scene shows both the cow and the bull looking very happy.
One of the first lines Muffy tells the male protagonist is that she thinks he is sexy.
When showing your infant son to Muffy she sometimes says this:
Muffy: Daddy's always giving you hugs. He's got no time to play with Mommy now...
As an adult, Lumina will say "Sometimes you can see animals running around being "lovey-dovey".
One event in Cute has your friend, Mimi, telling you how she envies you. She married for convenience, whereas you married for love. She wishes she had as nice and romantic a man as your husband. What's so odd about that? She decides to rectify this by announcing that she's going to have an affair with your husband. Your character performs the Heroic Mime equivalent of giving her three "Oh-no-you-di'n't!" snaps, and she tries to cover herself by claiming she was joking. And this isn't the only adultery joke in the game, oddly...
In Cute Rock asking you if you would like to hang out with him at the beach. You are married and he is not. When he realizes that you and him are the only two on the beach, he begins to get a few ideas...but quickly decides against it since he doesn't want your husband angry at him for the rumors about you having an affair that could get around.
The idea that you can impregnate Leia is just so ridiculous that the developers couldn't resist making Dr. Hardy lampshade it.
Rather than just making you or your spouse pregnant like in most games, you actually plan to have children in Animal Parade. But when you do so, your spouse makes comments along the lines of, "Well, if we're going to try to have kids, we've got our work cut out for us! <3"
In Animal Parade, several of the rival children will talk about the stork as you befriend them, but Heath's (Phoebe's and Calvin's son) comment is a bit risky.
Heath: Dad says the stork doesn't bring babies. Then who brings them?
Gill has an infamous quote in the Japanese version of Animal Parade, which was removed for the English translation:
"I want to lock you up in my basement and keep you all to myself."
One of the date options for Hiro is "Hiro's Room".
Likewise, one of Oracle's date options is her house.
A post-marriage line for Mikhail is "At night, your voice is like a serenade to my heart." He adds that it's his favorite time of the day.
This game zigzags the animal breeding issue. On one hand, there are no more Miracle Potions, the livestock trader simply takes the animal off your hands for a couple weeks before returning them along with a baby. On the other, this makes complete sense: it's quite clear what goes on at a stud farm.
You can marry the nun Alisa but she has given herself to the Harvest Goddess. You can't have kids with her. It's all but said that you two don't have sex.
The Harmony Day events. You can still give treats to the bachelors/bachelorettes even after you get married. And on their corresponding holiday, they'll still come into your house to give you treats. A few of the bachelors even specifically say what a shame it is you're married and then proceed to hit on you anyway.
If you marry Soseki, he will sometimes say that the pleasant weather makes him want to take a nap... and that he's hoping you'll join him.
If you wear a maid outfit, Allen tells you that you should wear it around the house.
Raising Klaus' affection may have him mention that, if the player continues to be nice to so many men, she might end up getting devoured by a big bad wolf.
His second Heart Event involves Klaus talking about 'other activities' that can be done at home and asks the player if she wants to come over for a visit some time and try them out.
If the player is married to Mistel, some mornings he'll say he heard you saying his name in your sleep last night and wondered what you were dreaming.
A little piece caused by Gameplay and Story Segregation. Mistel's festival victory dialog if you're in a relationship or married with him has him talk about celebrating your victory later in the evening. Outside of your respective birthdays, the two of you can not dine together while you are in relationship but not married yet. Maybe he was thinking of another way to celebrate...
Proposing to Iris has her mention that she's an 'adult' woman and has a 'lot of experience'.
Klaus' "How were your dreams, and did they include me?" line can be interpreted as less than innocent.