Hello,

I am so sorry this happened to you. That sounds awfully traumatic, and it's understandable you would be very upset and confused at your ex-partner's actions. Here's what I think happened: it sounds like your partner, although she seemed perfectly comfortable, happy, and content in her relationship with you, got distracted by Shiny New Thing, and swept up in the possibility of New Relationship Energy (NRE) with this other person. These things unfortunately happen a lot, because we humans are distractible and inconsistent creatures.

Your relationship was well past the infatuation stage, and it sounded quite companionate. If we are not careful about taking stock of what we have, and showing gratitude and appreciation for our partners and the love and stability they provide at this later stage of relationships, we may "grass is greener" ourselves into a hurtful situation because we feel a rush of attraction or infatuation toward someone else. It sounds like that's what happened to your partner -- she got swept up in a new attraction, and the feelings and neurochemicals probably overwhelmed her a bit and convinced her that she had to leave you to find happiness and truer love. She may find infatuation and good sex, sure, but she won't find what she had built with you over 4 years, overnight.

If this was something that she felt she needed to get out of her system, she could have communicated it to you, and divulged that she felt a strong attraction to a coworker. She wouldn't have even necessarily needed to have acted on it, but you could have discussed mutually if that was something you would be willing to allow in your relationship (specifically, the exploration of ethically hooking up with someone else). Or perhaps her gravitation toward this other person was due to her feeling a lack of sexual excitement and that sort of NRE (it's a drug, seriously) -- that sort of thing can be discussed, and mutually worked on to mitigate.

As an aside, I would question the ethicality of sleeping with a coworker, particularly if there is any sort of power differential (don't f*ck up, or down). I would be interested to know the justifications your partner had for this action. It's just never a good idea.

My advice is this: sometimes it's reasonable to reunite with an ex, and sometimes it's not. If there is a lot of hurt, it takes a lot of work and making amends to ensure a reunion would be healthy (I wouldn't immediately forgive someone without a lot of discussion about the hurt, why someone felt and acted the way they did, what they were thinking, their motivations, etc. and discussing how that person would behave and communicate differently going forward). I have had a partner somewhat spontaneously and out-of-the-blue leave me for someone else before, and it was definitely a shock. They didn't return, so I had to make peace, let go of my hope of reunification, and practice self-care to help me move on.

Are you currently still in a No-Contact period? Even if, as in this case, her actions of leaving out of nowhere and enforcing a no-contact period appear drastic and hurtful, it's important to try and honor it. Except -- do you still live together? I assume you share bills? It's 100% not fair for her to completely abandon your shared household and impose complete no-contact, when you presumably manage tasks as a team. But if she moved out and decided this is what she must do, you unfortunately can't stop her.

But right now, it's imperative that you do your best to continue your daily routine, practice self-care (however that looks for you), and get plenty of social time with friends out of your home. Prepare yourself for the possibility that your partner may not realize her mistake and reverse her decision, much as you understandably hope for that. And if she does revert, be prepared to have some very important conversations about her behavior and communication before you blanket-agree to forgive and let her return to your life.

I hope some of this helps!