Yes, it has happened that the bride or the groom ran off the altar - or even earlier. But what good ever came from that? True love, pah. In fairy tale maybe. In real life: Conflict. War. You have to think of your land and people as a competent ruler. Even more if you rule with an iron fist, as the Earthlings say.
This still holds even if the partners are from different species. One has tentacles, the other hand and feet. One has orange skin, the other green slime. One is from Drenthanx, the other from Tamaran. What's the big deal? Hecklers use to scoff it's already bad enough a difference that they male and female. (As a galaxy-wide known Earth saying goes, men are from Mars, women from Venus.)
What I think of the deal personally, well that's a completely different thing. Do I feel my betrothed is utterly revolting? Yes! Am I scared of the wedding night? Yes!
Luckily, as a royal, you have certain privileges. Connections. It wasn't hard to bribe Beast Boy into playing a stand-in for me, and he will keep his green mouth shut if he ever cherishes his appendages. And of course none of this note will ever leave my chamber.
Signed, King Glgrdsklechhh. For My Eyes Only.
The End