I forgot where I first heard this comparison being made, but I was wondering if there was a real historical connection between the two. For example, this 'Oath of Fealty' sounds awfully like a modern wedding vow (from Wikipedia):
By the Lord before whom this sanctuary is holy, I will to N. be true and faithful, and love all which he loves and shun all which he shuns, according to the laws of God and the order of the world. Nor will I ever with will or action, through word or deed, do anything which is unpleasing to him, on condition that he will hold to me as I shall deserve it, and that he will perform everything as it was in our agreement when I submitted myself to him and chose his will.
Well 'fealty' is just a 'Frenching' (an anachronistic Frenching at that) of the Latin, fidelitas. the proper translation of (iura/iure) fidelitatem as it appears in our sources should be an oath of/sworn fidelity. Fidelity oaths are just promises to keep your faith with specific clauses (in the case of this oath, to love all he loves, shun all he shuns, etc.). Neither oaths of fidelity, nor being sealed by a kiss, necessitate a feudo-vassalic bond emerging, although a lord might use the occasion to announce a grant of land to his new wife as Gruffudd, thirteenth-century lord of Bromfield, allegedly did (at least according to his wife Emma in the 1280s). Women usually had their marriage portion, which could occupy a strange position in law as it was both hers and her husbands, and yet remained a part of the wider family, leading to awkward situations should one partner die earlier than the other.
Vows are a verbal contract, and fidelity oaths are a publicly sworn and witnessed pledge to keep your faith. In that both originate in a period before a thorough tradition of keeping records emerged, yes the two are related. In content, not so much.