She married Vergnoux, her coach, in early 2005, and became a French citizen a few months following the marriage (June). In November 2005, Popchanka was cleared to swim internationally for France, following a 1-year sit-out from competition which was not waived by the Belorussian federation following her departure and last swim for Belarus at the 2004 Olympics. Because of this timing, Popchanka was unable to swim at the 2005 World Championships to defend her 200 m freestyle title from 2003.
Since November 2005, she has competed for France. Leading up to the 2008 Olympics, the couple lived in Edinburgh, Scotland, where Vergnoux coached from 2004-2008. Following the 2008 Olympics, Vergnoux and Popchanka moved back to France, after Vergnoux left his coaching job in Edinburgh for one in Paris.
Vergnoux is notable in his own right: during his time in Edinburgh, he was twice named British Coach of the Year. He also served on the British Olympic Team staff for the 2008 Olympics.