I think if Tyrion and Sansa are going to meet again (whether they remain married or not) then it is not going to be a happy reunion, their marriage was full of pain, on both sides, and even though Sansa does now seem to realise that Tyrion was nice to her, I don't think its enough to make her 'forgive' or accept him. (I say 'forgive' because the only things in their marriage he needs forgiving for really are being a Lannister and not being a knight from one of Sansa's songs, neither of which are really his fault.)