His family says they really like me, but they’d never accept me as his wife since I’m not Arab

Who is saying this to you? Are they saying it, or is he saying it?

Because if his family says that they really like you but they are not willing to accept you as part of their family if one of their own desires it, then no matter how good they think their reasons may be, they don't actually like you. They are just making excuses.

And if he's the one saying it and you've never received any kind of verbal confirmation from, say, his siblings or parents about the topic, I would be highly suspicious of his motives.

I think that this is a larger discussion that has to happen with your boyfriend. Telling him how playing second fiddle to another woman would make you feel might give him some much needed perspective. If he's not willing to budge on the traditional marriage, you have a choice to make - you can continue to be with him and reap the benefits of the relationship, but you are going to accept that eventually he's going to push you into a situation that you cannot tolerate (being a mistress, essentially) and you are going to end up with nobody and all the time and years of your life that you can never get back spent cultivating the failed relationship will be lost.

On the other hand, there is a nonzero chance that he might change his mind. Maybe money isn't as important to him as your love and affection for him is. Maybe he will mature a little more and recognize the importance of keeping someone he knows he cares about close, rather than taking a chance on someone else who just happens to be of the same race. But that's a lot of "maybes" and "what ifs".

Personally, I would draw a line in the sand. Like a savvy gambler, you have to know when to quit while you're behind, because losing the relationship will no doubt be hard for you emotionally, but you know what's worse? Losing the relationship anyway after trying for years to salvage it and then realizing that you wasted that time of your life chasing someone who didn't value you instead of hitting the dating scene right away. If you straight up tell him that you want to be his #1 and only wife, and he rejects that, you should leave him. Stick with him for the sex and the company if you want, but don't hesitate to put yourself back on the market, and take time to start emotionally distancing yourself from him.