Wah thanks for the tag lol

Hi TS,
As your initial emergency response, don't bother trying to find out on your own where did you do wrong. Instead, assure her with words and back up with actions: you'll let her cool down for a day and enjoy her me-time at the Airbnb, meanwhile you show your care by sending her meals at the Airbnb. Next day you call to ask show up at her door then have a calm and slow talk. If you want to save the money and stop her from going to Airbnb then give her space, time and love at home.

Key points:
- don't aggravate fight/flight/freeze response. When conflict escalates, people tend to resort to 3F, which is reflected as being defensive or avoidant. You can't solve a problem if you don't understand, and you can't understand if she won't talk.
- she feels unloved so the last thing you want to do is reaffirm that thought, so shower her with extra care when she needs it (while cooling down at the Airbnb).
- give yourselves time limit for the cooldown to align expectations -- no one should feel like the other is avoiding forever, but you want enough time and space to sort your thoughts.

Once you're in talking mood, you can try to understand more from her. I can imagine a few scenarios:
A) "too kind"?
She must've seen something you did that she felt was overboard. Maybe you were "too kind" at one point, while in your head, you're just trying to be the nice host.

B) language barrier?
Can she speak Chinese? If not, then it's not nice to talk in Chinese as she would be left out in the conversation. I also struggle with this as my bf is banana while I'm already used to Cantonese with my family. I try to translate at the end of every paragraph so he agak2 gets the context. That said, your wife may have stronger desire to mingle so she may have felt bad being left out at that time. Your laughters with your SIL without context to her could've sparked the jealousy.

C) other historical problems?
You'll have to hear more stories from her to find out... Maybe her relationship with her brother isn't so well, or she had some beef with her SIL in the past, she has negative bias towards her.

Btw, women tend to connect things more than men, so man may think that one problem isn't related to another but say that to a woman, she'll be upset you're trying to dismiss that part of the problem. She may also get to that conclusion if you happen to accidentally ignore her when talking to others.

Hi, sorry but I don't have experience there as I'm not married I can only try to help you understand women's perspectives or possible problems in your relationship.

I'm afraid I have to disagree with your statement that age = mature. I know a few who are way older but can be childish at times. Yknow how sometimes you feel difficult to deal with certain stubborn elderly who wants everything their way? Yeah that's immaturity to me. In your case, I don't want to label her yet because some of your examples are too generic and we don't have her side of the story.

Back to her jealousy, I think I can understand a little why she reacted that way:
A+B combined does paint a picture that you treat her SIL better than the other 2 guests. You both gel better in conversations somehow made her magnify onto your actions with her so anything "extra" could trigger her alarm. That said, I personally find it strange still, because her jealousy implies that she doesn't trust her SIL either.

As for C), it's common in a group discussion setting that one may feel shunned if s/he gets interrupted every now and then, even more so by own partner. For example, I have felt upset before when my bf interrupted me in a conversation as it made me feel unheard. We argued, and then we would both say what's in our mind. Apparently, sometimes he just gets a pressing question in his head and he'd have to get it out immediately. Understanding that, gave me the awareness that he's not doing it on purpose nor to spite me, so even if I feel annoyed, it's not something I should lash out at him, so I'd show a pouty face and he'd know. To me, this argument was a good one, because we understand each other a bit more to know how to react to the same situation again next time.

From what you say in quote below, your arguments went nowhere and you shoved all the problems under the rug. Both hold grudges and now the ugliness is seeping through. I'm not sure what went wrong, but you both need to learn to read each other minds -- think of arguments like an open book test where you're supposed to ask flip to the right page to get your answer (ask the right question in a right manner). If she reacts defensively all the time, then maybe it has something to do with the way you bring up the issue, e.g. yelling, or aggressively calling her out.

Back to her jealousy.... I like nihility's idea on handling guests in the future. She clearly has trust issues, so try to adjust to her boundaries to earn her trust. If she has issues with you + SIL, then you ask her to take over so you don't have to interact as much. Be careful though, it'll be a big red flag if she starts restricting every interaction with the opposite gender, as there's a limit to how you can control and beyond that, she needs to address her own insecurities.

Besides that, I think one of the ways is to show your affection in ways she'll pick up. Try everything you can: sweet talking, smooth jokes, acts of services, physical touches, gifts etc. I don't know what floats her boat, you'll need to figure that out. If she's convinced you love her, then I think she's more likely to have "good faith assumptions" of you.

"Listen" is one thing but I think she's looking for visible change. It's not easy for sure, but it just seems like she has some expectations.

Regarding chores, I really liked the other guy's suggestion in the original thread. Switch your positions for a week or month to understand each other's daily life. The key is to really try your best to understand.