Why is it a romantic failure? What might be a failure to you might not be to him, it's all based on person to person.
If she is banging a bunch of dudes behind his back then yeah say something, but if it's just her personality or something then I'd say leave it.
“Anna, my strong, terrifying Anna.” -Cas
"You lack the testicular fortitude to study under me" -Elodin
“slow and drunk is no match for fast and scared shitless.”-Jacob