Complex sentence: After the international success, the couple competed in "Bailando 2010" (the Argentinian version of "Dancing with the Stars"), since they were voted off Showmatch (in round 11) the relationship of the couple has been fraught.
Split into simpler sentences: After the international success, the couple competed in "Bailando 2010" (the Argentinian version of "Dancing with the Stars"). Since they were voted off Showmatch (in round 11) the relationship of the couple had been fraught.