Relax, dude. Your man is safe.
"Who loves him more than me?" literally means "who loves him more than (he/she) loves me. " That is entirely different from "Who loves him more than I (do)."
I think the Vietnamese sentence is ambiguous, since the object and subject pronoun is the same, unlike in English.
Id be interested to hear from a native Vietnamese speaker about whether the Vietnamese is also ambiguous.
"Who loves him more than I do?" was accepted as a correct answer. ;-)
The Google translator speaks to me: "I-ê-u", while here I only hear "I-u" with no "schwa" sound or anything of the "ê".