Complex sentence: Beatrice arranges for Marco and Rodolfo to move in with two immigrants in the flat above, while Eddie preaches to Alfieri that he believes that the kiss has proved to him that Rodolfo is gay and is only marrying Catherine for citizenship.
Split into simpler sentences: Beatrice arranges for Marco and Rodolfo to move in with two immigrants in the flat above. Eddie insists to Alfieri that the kiss has proved Rodolfo is gay and is only marrying Catherine for citizenship.