@Fauchard : Some options:
1. She married her husband to gain power (see: the trash in this chapter trying to do the same) because being female is a disadvantage to being chosen. It backfired but by now divorcing would just be digging the hole deeper.
2. It's a misunderstanding and the husband is a total SIMP for the aunt, but politics would include the families so grandpa is still right to be wary.
As for what happened to them. If she is that smart the aunt would likely saw the writings on the wall and just leave to stay with her husband.
After all those trashes would likely disown anyone not part of their thieves gang so this in turn spare her from their downfalls.
Heck, maybe the aunt even was part of the 2nd prince faction, if her husband is smart enough to even make grandpa wary he should've seen what Tia saw coming in the 1st life.