>Sansa would have known that LF is a only interested in
>himself and does not care about her. Although, once Sansa
>realizes how much of a lunatic Ramsay is, she will probably no
>longer trust LF as she will assume LF knew that Ramsay was a
>psychopath and blame LF for whatever trauma she is about to go
>through.
>
>If Sansa somehow survives this marriage and is able to get
>revenge against the Boltons and retakes Winterfell. LF will
>probably have lost Sansas support and perhaps have created an
>enemy.

Some assume she trusts LF, She doesn't. I think she's just playing her position until she figures out her next best move.