You also can't use diplomatic (or undiplomatic, as in this case) marriages of kings as normative; those were about solemnizing access to troops and taxes *and* not generally subject to anyone being able to tell the king what to do.

The normative marriage customs would hinge on "when can you expect to support a family?" questions (which is why the grooms are substantially older than the brides) which are diluted for the nobility. The corresponding nobility issues weren't around money, as such, but "what if this alliance is a mistake?" They were entered into carefully and cautiously for the most part.