My (27F) boyfriend (26M) is falling in love with his wife (25F) and I don’t know what to do.

I know the title sounds weird but please read the whole post before judging.

We’ve been together for 8 years. Our relationship has been almost perfect, and I love him more than anything. Unfortunately, his family hate me and made it clear that they would disown him if he ever married me. My boyfriend is very close to his family so I accepted it would never happen, especially since their dislike was my own fault. I said and did some things early on in our relationship which I wish I could undo.

3 years ago, his dad told him he wanted him to marry this girl, who I will refer to as Juliette. Neither of us comes from a culture where arranged marriages are normal, although in his family there have been a few cases in the past where marriages have occurred for strategic/business purposes, so we were both shocked and angry at his suggestion. My boyfriend immediately refused but eventually, his dad said something that convinced him to at least meet her. To cut a long story short, they got married 2 and a half years ago. I didn’t go to the wedding, but it was everything I had always wanted, and it hurt seeing him marry another woman.

Before they got married my boyfriend told her all about me and explained he didn’t plan to break up with me even if they got married. She was fine with it as she didn’t want to marry my boyfriend either but was being forced to by her uncle. All three of us met up a few times to figure out what things would look like after they got married.

My boyfriend and I started keeping our ongoing relationship a secret from his family and our friends because we knew there would be a lot of push back from everyone. This meant I had to move out of our shared home and had to go back to the job I had given up two years prior. I was willing to do all of this because I loved him, and he continued to be the perfect boyfriend to me. He spent all of his free time with me, but he went home to another woman.

A year after they got married, his family started questioning why she was still so shy and skittish around my boyfriend. After discussing it, my boyfriend and I agreed he should spend some time with her so they could at least become friends so his family would get off his back. I think this was a huge mistake on my part. Suddenly, my boyfriend was talking about her a lot and was always worrying about her. He was going out of his way to do things to make her happy, and when I voiced my jealously, he would justify himself by saying he thought she was depressed and that his family would be upset with him if they thought he was mistreating her. The worst part is that he has done things he wouldn’t even do for me, even though I’m the one he claims to love, for her. He has also started cancelling on me if he thinks she’s been alone for too long or if she asks him for help with something, usually with very little warning.

The thing that really convinced me that he has some feelings for her though was during a social gathering when another man was openly flirting with her and he got all territorial over her. He claims he was doing it to keep up appearances, but I’ve known him long enough to know he was genuinely angry/jealous.

I want to save my relationship but I don't know what I can do at this point. He denies being in love with her and claims his feelings are just platonic but I've seen the way he looks at and speaks about her. So, what can I do? I have considered telling him I want him to divorce her but I don't think he'll respond well if he thinks I'm backing him into a corner.

TL;DR – Boyfriend of 8 years married another woman 3 years ago. She agreed to an open marriage and we continued dating. The more time he spends with her though, the more I think he is falling in love with her.