In this situation I am a sponsored person.
However if I put myself into the sponsors position for a moment...I am duped into a fake marriage, shortly after my spouse arrives the relationship breaks down. I dont know the statistics but I assume there are a significant number of people who through either immigration barriers or sheer distance from each other cannot spend extended periods of time together before PR is granted. So this person has scammed me and now they are likely to start making false claims of abuse/neglect to protect their PR status. What if I as the sponsor am being abused by the person I sponsored?
As the sponsored person I sell my home, give up a well paid job, move away from my family and friends to be with the person I love. Potentially for the same reasons above extended periods of time together have been impossible. Same again relationship breaksdown. Through no fault of my own I now have to pack up and return home, unless I want to make false allegations of abuse aginst my sponsor.
There has to be legislation that accounts for the genuine case where despite the best intentions of both parties it does not work out. In my opinion this legislation will not deter the determined fakers, sponsor or sponsored and dont really see the sense in this legislation not being tied into the time period that a sponsor is obliged to making an undertaking for. However neither can we have sponsors insisting on deportation just because they might have had enough of their spouse for whatever reason.
I dont have a categoric answer, but possibly think toughening up on deportation and re-entry rules when there is clear abuse of the system might be a starting point.