Crowning with laurel is the central part of the eastern christian marriage rite, dating to at least the byzantines. Greek and Arab christians normally use stylized laurel leaves but still occasionally real ones.

Slavs have mostly dropped the laurel/triumph connection and just use a replica gold-jewels-and-velvet crown. Though the ones I've seen are still engraved with patterns suggesting plants so there's at least an allusion to the older tradition even there.

I don't know what connection a 17th century english royal would have felt towards this tradition but given that period's fascination with antiquity it may have been a common association. I also don't know where the byzantines got the idea, but it feels like one of those pre-christian mediterranean things they adopted. I know laurel crowns were used for all sorts of ceremonies and festivals in greece & rome, not just martial victory. A wedding is a kind of triumph I suppose, it would not surprise me if this is an ancient tradition.