Could Isobel be the solution for Mary and Matthew?

Watching the trailers for next week's episode of Downton Abbey, it's clear Matthew will have a decision to make between Mary or Lavinia. According to some previews, he's likely to stick to his conscience since he's already engaged to Lavinia ...

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BUT ... could this be the selfless act that Isobel is so desperate to prevent according to the series 2 press pack? Not sure exactly what her methods could be, but she would certainly have allies in Robert and Violet, and maybe even Anna or Carson?