AIO to my partner’s relationship with a female coworker
So my(28f) partner(32m) of 10 years has been working with this girl(28f) for at least a couple years now I think. They sit next to each other at work and seem to have gotten close. I’m not too sure when this friendship/relationship started because I was a bit blindsided by it, I always just thought we had a mutual understanding that we wouldn’t get close to opposite sex coworkers, I have a bunch of male coworkers I talk to at work but do no talk to outside of work hours or have any of their socials out of respect for my partner. But one day I noticed on his phone he had a very long dm thread with this girl from work.
They had messaged each other something that I decided not to open but instead ask him about. But when I went to confront him the message was already deleted. He swore to me it was only work related memes they were sending back and forth and that he was scared what my reaction would be so he deleted the thread. This just made me feel more distrusting about the whole situation and since then I’ve seen disappearing messages be turned on and off and messages just straight up being deleted. They have even started messaging each other while he’s home with me which is something he never did before.
I’m not sure what to do from here because since I have been lied to/kept in the dark about this friendship I honestly don’t approve of it. This is a boundary he set for our relationship as well because he never liked when I had relationships with coworkers or my exes on social media. So much so that he has taken my phone and blocked my exes without my knowledge(he has not done this in years but that set the precedent for me)When I mention all this to him he tells me he will just block her or unfollow her but he never actually does. It almost seems like a cop out when I am asking him to explain himself and he just throws his arms up and says “I’ll unfollow her if it makes you less worried”. It’s not even what I am asking of him because I feel like if I did make him block her he would only be more secretive about the friendship. I don’t understand what about this relationship is so fulfilling to him when all I see them exchange is memes related to work. It makes me believe they are closer than it seems and that he has developed some feelings whether he admits it or not. He has never crossed this boundary before with other women at work, but this girl is my age, very attractive and also Latina(basically his type) me and my partner also have a more alternative style and recently I’ve noticed her style/aesthetic had drastically changed on her Instagram. She went from looking like she listens to rap/hip hop to posting bands and taking pictures in all black and fishnets.
What’s eating at me inside about all of this is that I have lost the security in my relationship and I basically feel like I am competing with someone now. I have never felt so insecure or like I just can’t trust what he is telling me. If it really is just innocent how do I get over these feelings? Or should I trust my gut in believing that there is more to this relationship than I know?