Viera Lore Question

[Iscah]

There are always exceptions to every rule, and even if you visit Fanow amidst its traditions, you'll see Cymet is rather openly plotting to leave the wood despite it being something of a taboo.

It's not taboo to leave, only to return. (And even that seems to be on the verge of changing.)

It's a major decision that few undertake because it means cutting themselves off from their society and losing connection with the voice of the forest. But it's not something they're prevented from doing, and they have specific rituals to remember those who left. There are a few sidequests dealing with aspects of this.