Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Tear Jerker: Harvest Moon
The very end of Harvest Moon: A Wonderful Life. No, not your character dying, or even your child getting married. The very last line your character speaks in the game. When your wife observes how you've both gotten old, and aren't the glamorous young things you used to be.
Your Character:You're still beautiful.
Previous to that; given what a Sugar Bowl the series usually is, Ellen's death in Harvest Moon 64 doubles as this and the closest thing the series has to a Wham Episode. Elli's reaction just drives the trope home.
What about Nina's death? You never expect it, plus most people don't become friends with her in time.
Screwing up anyone's love life. For example: making a character leave the game (like Kai or Cliff), turning down a character, choosing a bad option in a love event, or (sometimes) courting a character. It's even worse in the Wonderful Life series, especially in the first game. If you court a character and marry another, they'll go to your house crying and basically give you a "You Suck"speech.
Out of all the "betrayed" scenes in A Wonderful Life, the saddest has got to be Muffy's. Let's just say that if you don't feel bad about getting Muffy to four hearts and then proposing to someone else, then you have no soul:
Muffy:I thought I didn't want to see you again. But I had to go and do something stupid. Coming here... I was serious about you.
I remember when during my first gameplay I courted Celia and married her. I had also made friends with Nami, and during the cutscene with the MC and Celia telling everyone in town the 'good' news, Nami walked away with a pained expression. I had never felt so guilty.
Animal Parade: What Gill says in the Japanese version of the game if you tell him you don't like him back when he confesses to you.
Gill:I'm sorry. I wasn't trying to push my feelings on you. If there's someone else, you should tell him how you feel... Thanks for today.
In Animal Parade, after marrying the Harvest King and maxing out his affection for you, his maximum-affection line drives home the full effect of your very different lives:
"After you are gone, I shall love what you loved. I shall sing the songs that you sang."
In Harvest Moon DS, most of Galen's dialogue post Nina's death is pretty sad, especially when you imagine him going to bed and living alone in their little house every single night.