Frank Kogan

the reason it's a puzzle is that "[verb]ing" can be a present participle (viz an adjective) or a gerund (viz a noun): and they often don't have enormously different signification

"i can't bear angel being morose" <-- being is an adj
"i can't bear angel's being morose" <-- being is an noun

both of these are fine grammatically, and the meaning distinction is nugatory -- the second it's the mood you're reacting against, not the person, except same diff in the circs -- so you end up making the choice on rhythm and stuff like that

also:
"i can't bear angel, being morose" <-- the morose one is you
"angel, being morose, is unbearable" <-- the morose one is angel
"angel's being morose is unbearable" <-- it's the mood that's unbearable not angel

you've double up the puzzlement with "her" bcz (as you say) it's not clear if it's a possessive her or the accusative of "she" -- either works! but you can pick Angel or Angel's or indeed "she")