I admit that I'm not completely acquainted with all the subtleties of President Snow's and the revolution's views and usage of Katniss Everdeen for their goals in The Hunger Games: Catching Fire. What I wonder is, why does Snow urge Katniss to keep up the masquerade of her love to Peeta (much to Katniss' dismay).
Doesn't the supposed love between Katniss and Peeta draw a much more favourable view of them in public (which I'm not sure is really in Snow's interest)? I think revealing that their (or at least her) love was only a staging for their survival would have shown her as opportunistic and duplicitous and could have shattered her image in public to some degree. All in all that acted love had only advantages for Katniss and Peeta, and is even employed for exactly this purpose again by Peeta when he tells of the supposed pregnancy.
So while I can understand Katniss personal aversion to keeping on acting this false love, I'm not sure I understand President Snow's reasons for furthering this masquerade.