Bore up against implies an encounter or collision of some sort. Antonyms for the phrase may include "avoid," "sidestep," "divert," or "dodge." These words suggest an attempt to evade the situation, rather than engage with it directly. Other antonyms may include "embrace," "loosen," or "relax," as these words indicate a willingness to let go and allow things to happen naturally, rather than trying to force a certain outcome. Ultimately, the choice of antonym will depend on the context, as well as the speaker's perspective and intentions.