I think I know the answer but it's bothering me so much I'm starting to wonder if I'm overreacting.
This is long sorry, there's a lot more I could say!
I work in a regional account manager role looking after commercial relationships, I'm one of 4 account managers across the UK in the business. Over the last few years I've built a good professional relationship with one account, growing it to be a key partner.
A colleague has always joked that she has a soft spot for the owner of this account. I didn't worry about it as she is generally very loud, flirtatious etc and pretty much showers affection and praise on everyone. Several months ago I started to feel like she was undermining me either this account, she was trying to build friendships with team members - even having one staying at her house before a conference. I bit my lip - partly because I dislike drama and partly because she has worked with our manager across different companies and I felt like he would brush it off.
3 months ago she was at a conference she also attended and within weeks had started a relationship with him. She told me and my boss a month later. After mulling it over for a few days I told our manager that I was unwilling to continue as the account manager, and told him in writing the things that I'd kept to myself in the lead up to this. I was very clear that professional boundaries has been trampled on for months and that if he didn't nip things in the bud and be very clear on his expectations that the situation would become impossible to manage. I was unhappy losing the account but felt I had no choice. The industry is very sociable and everyone knows everyone, and the idea of me managing the account while she was heavily involved in the social side of the business wasn't something I was comfortable with. My manager agreed that he couldn't expect me to continue as the account manager.
Everything I predicted has come to pass - I've been on a teams call with my colleague and seen him sat on the bed at the side of her with no shirt on, she's embedded herself in his business in a way that is incredibly unprofessional, he has been working from our office and been there while we've had team catch ups. Throughout this I have spoken in depth to my manager about the impact it's having on me - losing my largest account has left me unmotivated and feeling like I'm not important to the business. It's being talked about on a very negative way in the wider industry and is just a whole load of drama that I don't need in my working day.
She has been promoted, and I just can't move past the fact that this means our business is essentially saying that we are fine with this. She's attending industry events she hasn't been invited to because he's there, and now suggesting away days and ensuring he is part of everything we do. My manager says he is now going to speak to her about professional boundaries but I feel it's too late, the time for that discussion was before she was promoted. She's still undermining me and other colleagues, taking credit for our work and involving herself in our accounts. She has openly said that the only reason other colleagues get praise is because our manager is worried we'll leave. He's aware of this but doesn't manage her as there is so much drama when she doesn't get what she wants. I need to leave don't I?