I Have Trust Issues

Our daughter turned 3 months a few days ago. Last week my Latina wife told me she would like to return to her country "for a while". Her mood was casual when she said this, but her intention was much less so. I know my wife is homesick and I know she yearns for the support she'd get living among her family. When you have 10 siblings, you still will get a lot of support, even when 2 are mentally incompetent and several others live far away from where she would.
I'd have a hard time allowing my wife to take our daughter away for a period amounting to months. I also wouldn't like having her in what could be the most dangerous country in the western hemisphere w/out me.
But what really bothers me is the thought that her homesickness would overcome her, and she'd decide that she/they would be happier staying in the only country she knew for every moment of her first 40 years of life. This would, of course, require her to break an oath that I would have her make before leaving.
So far she's never shown her integrity to be anything less than perfect, and I've long been comfortable w/the idea that it is perfect. But her homesickness would put a greater strain on her than she's known in recent history. Furthermore, with all the perfidy I've seen in people who come into my life, I can't help but picture seeing myself in front of a lawyer sometime in the future telling me "sorry, bub, but you allowed your daughter to leave the country--you can't make her return." I really hope my wife let's go of the idea.