Sofia turned against Rafe after she overheard him talking badly about her to his friends, which is the clearest explanation available for her change in behavior. Beyond that, there is no reliable evidence in the material here that she did anything more dramatic than pull away once she felt disrespected.
The relationship reads as a reaction to betrayal, not a calculated move. Rafe’s own words seem to have been the turning point, and Sofia’s response was to stop trusting him.
There are rumors and fan theories around the pair, but this account supports only one solid takeaway: Sofia distanced herself because of what she heard him say.