Love rival drama is extremely common in this kind of stuff though.
It almost never succeeds but it's very common to end chapters on cliffhangers where one of the two members of the primary couple is poised to be taken by someone else which may or may not be a misunderstanding.
Besides, this was more or less a harem from the start. The title makes no secret about the fact that most of the princes' seem to be quite attracted to Liz.