It's definitely hard to do and since I haven't played those games much I can't really answer accurately, but does Larian (Baldur's Gate 3) do a better job?
I think the main problem with Fable or Mass Effect was that the game wants to converge to one of a few endings, but definitely for ME there's a bajillion decisions you can make until you get there.
I don't know if you can get rid of this "definite" ending thing per se; some games say they have X amount of endings, but again, I can't really name any. It's probably more gratifying to have more self-contained sub-stories where the decisions made e.g. an hour ago have an effect on the progression and outcome, but not too much longer than that. You should have the choice as a player to switch from e.g. "good" to "evil" partway through your playthrough. References back to previous quests and their outcomes are nice but shouldn't be as heavy as "your one choice made 30 hours ago affect the ending of the game in a significant and irreversible way"
I enjoy the way Baldur's Gate 3 implements this- choices tend to align more along character axes than good/evil. There are indications for many small dialogue choices that say "Karlach approves" or "Astarion disapproves" to give you a sense of each character's values and personality, and they each have their own motivations. Some are more traditionally good or evil, but they all have reasons for doing what they do.
Choices occasionally feel fairly binary good/evil, but more often all choices have their pros & cons, and it's more about story and narrative in making my decisions.
I think the main problem with Fable or Mass Effect was that the game wants to converge to one of a few endings, but definitely for ME there's a bajillion decisions you can make until you get there.
I don't know if you can get rid of this "definite" ending thing per se; some games say they have X amount of endings, but again, I can't really name any. It's probably more gratifying to have more self-contained sub-stories where the decisions made e.g. an hour ago have an effect on the progression and outcome, but not too much longer than that. You should have the choice as a player to switch from e.g. "good" to "evil" partway through your playthrough. References back to previous quests and their outcomes are nice but shouldn't be as heavy as "your one choice made 30 hours ago affect the ending of the game in a significant and irreversible way"