There are a few ways you can acquire this trophy.
The way I achieved it was to complete the quest 'Farewell Valmiro' which then gave me maximum affinity towards Valmiro and the trophy unlocked.
There are a few other ways you can get this aswell such as:
-Completing 'Dragons Tongue' Quest and giving the Arisen Bond ring to anyone you want to maximise their affinity.
-Completing 'Arousing Suspicion' quest will maximise affinity to Aelinore.
There are probably a few other ways to easily maximise affinity but I find these the easiest.