Antonescu flew to Italy at the time of the allied landing in Sicily with the proposal that Italy, Finland, Romania and Hungary leave the war together. Mussolini rejected the idea but if he hadn't, it might of worked. The sudden loss of his allies would cause the German position to collapse and end the war at least a year early. Something I'm sure Stalin might find tempting. Churchill would probably not oppose it either- the smaller axis players are bit players and athreat to no one.
I don't see it.
True, objectively Italy was much more on the level of Romania than of Germany - but not in politics, foreign policy and propaganda of the time. Italy was considered one of the three main Axis powers. Giving it a slap on the hand would be considered insufficient by the public opinion of the Allied countries which had a free one.
Secondly, by 1943 Stalin was already considering the post-war situation, and what we know of what he thought at the time doesn't lend itself to believing that he'd settle for a series of Fascist regimes carrying on as if nothing had happened, several of them along his borders. Quite the contrary.
Thirdly, by 1943 the British had reinstated the Negus on the throne, after having fully supported him in the war against the Italians in AOI. Giving Ethiopia back to the Italians? No.