The almaktoumfamilyfans IG was the first to congratulate Maktoum, and they tagged someone from the girls side. That person followed them back. So I'd say the news is legit.
Very recently, the same IG account wished happy birthday to the sheikh who was supposedly engaged to crown prince Hamdan. They said she 28 and still single. I felt bad for her. Looks like after Hamdan broke his engagement with her, nobody wanted to marry her. I heard in the Islamic community, if a girls marriage or engagement breaks she bears the stigma of that forever. No man will want to marry her if she was rejected by another. That is really so sad.
For the girls sake, I hope Maktoum does marry her, because if he doesn't she may never get married.