In this scenario, no, it's already a red flag that they invited him round without checking with me; my partner and I always check with each other before inviting anyone round.

In general sure, my partner does hang out with their ex on occasion because they're still friends.

---
'I will now punch my professor in the face because whatever punishment I will receive will not surpass the happiness I get when team salty mid loses' -Crows

Would you be comfortable with your girlfriend hanging out with her ex?

[none]

[none]

---