Other princes had done the same and there were already engagement announcements last time in some of the kingdoms in Eliora.
Arabella's marriage with Ferdinand was one of the most beneficial weddings that happened in Eliora before signs of war with Fynnia became noticeable.
Some kingdoms were even wondering if Lobelius noticed before them and acted accordingly to acquire such a strong ally and successfully got Valeria by using Arabella.
Of course, Arabella's parents and the elders in the kingdom considered the benefits of having Valeria as their ally. But the main reason was because of Ferdinand's marriage proposal and the monster attacks that her parents feared might keep happening again after the incident at the foot of Mt. Callion.