I dunno... I think the way it was presented I didn't mind it, or don't mind it much now. If she'd stuck with quitting in SSSC, after all her mopey talk about it, I would've been more disappointed. But she doesn't have to have the same adventurous interests as Alex, just as Alex's father didn't have to go with Dyne.
I need to reread the TSS text, I guess, but I don't recall her saying much about how Alex is more grown-up than she thought and ready for a solo adventure, etc in that game. Just that she's decided to return to Burg, and then her voiced farewell, which goes something like this: "I never dreamed we'd say goodbye like this... Oh, Alex, you have to come back to me. I'll pray constantly for your safe return. Goodbye, my love." I think there's another line about how vast the world seems, too. But no comment about doubt or even worry, much. Again, maybe I'm just filling in a perception of character from the relative lack of text, but I read this as confidence in him as well as security in what she wants to do -- she had her taste of adventure and decided that that was enough.
Of course, if she'd had to help fight the Saline Slimer in that game and seen how dangerous things really were, she might have felt differently.
The Weird Woods were also not nearly as threatening; no waves of goblins to fight off (and no nagging by her about Alex needing to practice his sword skills if Laike helps them fight.)