The phrase I've been loving you is not formal English.
Or so I'm told. I can't figure out what is wrong, though, please someone kindly explain.
I did google and found on WordReference the thread: https://forum.wordreference.com/threads/since-ive-been-loving-you-since-ive-loved-you.2778264Since I've been loving you/Since I've loved
The problem is I don't even understand why 'loving' (Post #3) is considered incorrect.
Spot on, Alex! The point here is that "love" is a stative verb. If you look at the British Council Learn English site here, you'll see that stative verbs are "not usually used in the continuous form, even when we are talking about temporary situations or states ..."
English is not my native language.