Atheist with a Muslim girlfriend

[I_am_not_mafia]

Have you considered the possibility that she was just placating her grieving parents by agreeing to put on a show of faith, for their behalf?

Especially as the parents themselves will be reminded of their own mortality with the aunt, their sister dying and will be thinking that they don't have too much time left themselves. They'll be putting pressure on the daughter because they want comfort themselves and so the daughter may be wanting to give them that comfort.