I agree with the spa treatment. Put a gift card in a "Enjoy your birthday" card. Let her make the appointment. You just cover the cost. Do not give it to her in person. Leave it someplace she will find it.
If I was in your shoes, I would have plans doing something away from her. Give her space on her birthday. You go do something manly.
Thank you for this. I did something like this, W said “thank you” and accepted the gesture. I was expecting her to get annoyed or something but I think she appreciated it but trying not to show it.
M: 28 W: 30 T: 2 years Married: Nov 2019 BD: 5 days after wedding (I know right?)