This.

She hid it for you. Being friends with an ex can be good, as long as all parties are over it, bd their new partners are OK with it, and everything is out in the open with appropriate boundaries.

But your partner needs to know. They gave a right to decide if it is a boundary for them and if they are comfortable with it.

A partner of mine once didnt tell me that a distant friend was a really old ex (think teens) until years into our relationship because they thought it wasn t mportant and they weren't close and rarely spoke so it didnt come up, but it was important to me and I felt hurt by the delay.

In the end it didn't affect our relationship but it definitely made it harder for me to like that ex or feel comfortable with them in our life because it's hard to get past feeling like you should have been told something.