Your boyfriend is being painfully honest. If it were in his power to change things he would do so, but he cannot. The problem is that whoever marries him must join his family, but his family refuses to accept an outsider. His parents don't want you or mixed-race grandchildren.
You grew up in a family and in a culture that is open and diverse. He grew up in a family and a culture that is very closed and insular. About half of the Kuwaiti people marry a relative such as a first cousin. While some of the Kuwaiti people will accept your marriage and your kiddos, his family and many others would not--and it would not be fair to your kiddos to live with that prejudice every day.
A mixed-race couple I know so left excellent jobs in Singapore due to the bigotry against their Chinese-Caucasian kids and came back to Canada, where they had met as students. Note that Singapore is not nearly as insular and inbred as Kuwait!
I know this is not easy to hear, so I am trying to encourage you. My (Millennial) cousin broke off his engagement to a lovely Vietnamese girl, after living in VN for a year and being committed to learning the language. Years ago, my sister was madly in love with a fellow student from Taiwan and was into the Chinese language and Chinese cooking. She would've had to move to Taiwan. In both their cases, despite the acceptance of the families, they had enough misgivings to walk away. A year or so later, they met and then married Americans and are living happily ever after.
As a matter of fact, I just saw them, their spouses, and their kids at a family reunion. The Millennial cousin lives in the Rockies and he and his wife just got back from a trip to India. They and their small children are thriving! So, let your boyfriend go, and let bygones be bygones, and be ready to open your heart to love in the next year or two or three!