Forever My Diamond now supports Steam Achievements! There's fittingly a total of 2, one for each ending. (Did you know the game has two endings? Well, now you do!)
It's also a little bit easier to get Grace's ending than before, so don't fret if you weren't able to find it.
(In some cases, previous save data may be incompatible, in which case you'll have to start a new game. It's only about an hour long, so hopefully it doesn't cause you too much trouble.)