Thank you so much Englishguygoinghome, you indeed know a lot about it.
So I only have two options I guess she renews her visiting visa since we only visit the uk for less than a month each time or apply for Surinder Singh (which I didn't know existed lol). https://www.gov.uk/apply-for-a-uk-re...rd/eligibility
Surinder Singh cases
You may be able to apply for a residence card as a ‘Surinder Singh’ case.
To be eligible, you must be a citizen of a country outside the EEA and:
the married partner, civil partner or child of a UK citizen
have lived with them in another EEA country where they worked or were self-employed before returning to the UK
be able to show that your UK sponsor based their ‘centre of life’ in the EEA country in which you both were resident before returning to the UK
You can prove your UK sponsor genuinely moved to another EEA country with:
proof of their address, how long they lived there and any other related information - eg if they bought a house
proof of their integration in the EEA country where they lived - eg whether they speak the language, have any children born there or were involved with the local community
You can find out more about retained rights of residence and Surinder Singh cases in the UKVI instructions for residence card applications (chapter 5).