Also in the Netherlands the royal marriage needs to have the King's consent as it is he who offers the Bill of Consent to the States-General by means of a so-called Royal Message, set in pluralis maiestatis (We = the King) and signed by him:
Herewith We offer into Your consideration [name of the Bill].
The explanatory memorandum attached to it contains the grounds on which this Bill is founded.
And herewith We command You into the Lord's holy protection.
The Hague,
[date]
Willem-Alexander
This is the first sign by the King, even before it is offered to Parliament. When the King really, really wants to obstruct, this is the first of his ultimate chances. The very last ultimate chance is to refuse to sign an Act of Consent. Of course a Government will only offer such a Bill when the King agrees with it, to prevent major constitutional problems.
As I understand it, all government bills before parliament are technically either introduced by the King or introduced on His behalf, but that is mostly a formality in a constitutional monarchy. The actual decison on whether to introduce a bill or not lies with the ministers, who bear political responsibility for the proposed legislation, and the King is bound to abide by their advice. I couldn't imagine a situation where a modern-day Dutch monarch would try to play an active role in controlling the legislative agenda of the government.
In any case, browsing Chapter 2 of the Dutch constitution, Arts 29 and 30 say that bills excluding someone from the line of succession if "exceptional circumstances arise" or "appointing a successor to the throne if it appears that there will be no successor"
must necessarily be presented "by or on behalf of the King", but apparently that requirement
does not apply to Art. 28, which says only that the two chambers shall meet in joint session to consider a bill to grant permission to royal marriages. Considering then that no inconsistency with Chapter 2 exists, my understanding (I may be wrong!) is that Art 82 (2) and (3) apply and, even if the King, in a very improbable scenario, refused to introduce the consent bill, one or more MPs could still introduce it in a joint session as a private member bill and not a government bill.
Of course you are right though when you say that, as a last resort, the King would still have the prerogative of refusing to ratify the bill once it has been passed, but, again, I don't think that is a likely scenario in a constitutional monarchy.
Just as a comparison, in Sweden, unlike in the Netherlands, the Instrument of Government removes the King completely from the legislative process in the sense that the monarch plays no role whatsoever in either introducing legislation or ratifying it (i.e, he is essentially powerless). Nevertheless, the Act of Succession by constrast
explicitlly gives the King a role in vetting royal marriages as the government is legally forbidden from consenting to such marriages unless the King requests them to do so, which I find somewhat odd.