Evolution of the MS companion radius with its effective temperature. The black line corresponds to the pre-CE evolution, while the dashed line represents the post-CE evolution. The colors indicate its log g during post-CE evolution. The red solar symbol indicates the onset of the CE evolution and the gray star the observed properties. During pre-CE evolution, the effective temperature and radius increase, but this is reversed due to accretion of a portion of the stellar winds of the WD progenitor. After ≈2.2 Gyr of post-CE evolution, the MS companion has properties that are similar to those of the G-type star in KOI 3278.