Shirley is USUALLY the kind of person who overplans and would be worrying right now, but she understands that reasonable goals are more important first, like getting her girlfriend of 3 months to entirely move.
This is a more reasonable expectation than bringing Wynn home before the sky’s right.

One of my friends is totally sure that Shirley and Siyav’s mother is a tree.

She is not a tree. But she also is a tree? It’s a thing, and probably not the exact thing you’re thinking.

W3Schools

Siyav: I don’t know HOW you’re gonna meet our mom.
Shirley: Can’t even begin to worry about that now.

Wynn: Ooh, why not?
Shirley: A hundred reasons. The sky’s not right. The wind’s too fast.
Siyav: We’d have to talk to a dozen beings first.

Shirley: It’s not personal, but Mama won’t come to us. And we can’t just bring outsiders there.