UK citizenship is granted by residence, not marriage. she had indefinite leave to remain (permanent residency), the only condition to keep it is you have to vi

UK citizenship is granted by residence, not marriage. she had indefinite leave to remain (permanent residency), the only condition to keep it is you have to visit the UK at least once every 2 years, she then spent 8 years outside the UK without visiting, so she lost it. she had the option of taking UK citizenship after five years residence, but chose not to as Singapore doesn't allow dual citizenship. she wouldn't have been granted government accommodation in Singapore as she would be a foreign national the UK border force is literally blameless here, if anything they were over-compassionate in granting her another visa after she overstayed previously, which lead to the eventual detention and deportation