I think you need to sit down with your wife and put aside all the ego to discuss. I think for her to ask for 5k, she didnt take into consideration that your pay is also used for savings for the kids. Maybe working out the figure and showing her would be clearer to her.

Tbh, the amount women spend for maintenance for physical outlook can be very costly. If your wife also goes for aesthetic clinic, then lagi gg. 5k not enough for her seriously and if she is into branded things... lol. So I think you need to understand her spending and see where she can just cut some unnecessary spending. I think if I'm you, I would propose 2-3k first and see how she spend. If she is not simply spending then can give her more after that. And on those important dates (I.e anniversary, bday), splurge on her a lil, buy her smth she has been eyeing on it, or take her out on a good meal so she feel appreciated.

If majority of your money you have already cater a huge portion into financial planning for your kids, then I think you need to enlighten her. That's why other husband can give but you cannot, cause your planning is long term. Not short term. Now your kid may not need this money, when they need who pay? From her 5k meh? She need to see the big picture since you are paying for all the family expenses.