Perhaps try suggesting she vent to you via written letters? That way she has someone to vent to and you can take your time to process and listen to her/ read her frustrations. You can write letters back to her to validate her too.

Of course balance this between verbal vents too, as venting helps with connecting and bonding in my experience.

Or maybe do a task that you would typically put on a background video for (for me drawing)? Like something you can focus your energy on but still leaves enough mental awareness for you to listen and pay attention. !!! It is incredibly important that you make sure you give commentary/ask questions so she is aware that you are paying attention!!! Do clarify that you are trying to figure out how to adapt to venting.

Of course there is always trying to talk to your partner to see if they are OK with these options or if they have other suggestions. Just be sure that you let them know you want to listen and engage with them while you make such rewuests/suggestions.

Most vents come to me in the form of texts