"Seeing through" means detecting the true nature of someone or something, often spotting lies. It can also mean continuing with a task or plan until it is finished, despite trouble.
Seeing through glamour is easy. It's people that are hard. Cassandra Clare
This is one of the miracles of love: It gives a power of seeing through its own enchantments and yet not being disenchanted. C. S. Lewis
Seeing through is rarely seeing into. Elizabeth Bibesco
Rashmika could tell when anyone around her was lying. But seeing through her own deceptions was another matter entirely. Alastair Reynolds
I'm tired of all the people I'm seeing through. Pete Yorn
It was finally becoming clear to her that love wasn't about finding someone perfect to marry. Love was about seeing through to the truth of a person, and accepting all their shades of light and dark. Love was an ability. Lisa Kleypas