I don't really understand this sentence. Could someone help break it down for me?
僕が同一人物だと確信に踏み切れないのはこの子の顔が半分しか見えていないからだ。
From the way I interpreted it, it would have a meaning similar to:
The reason I can't boldly believe she is the same person is because I can't see more than half of her face.
which I do not think is correct.