1) Witnesses are not required. Only God. Or another way of looking at it is, God is the Witness. The promise or "intent" to stay together is the covenant. The contents of that covenant are outlined in the Bible. If someone disagrees with or rejects parts of that covenant, they are rejecting the way God designed marriage, but a marriage it still is.Is it marriage if it doesn't include witnesses and a covenant between the two?
Is a vague intention to stay together recognized as marriage by YHWH?
2) This honestly perplexes me. How vague can "I want you to be my woman" be? Let me channel Yoda here: Intention or no intention, there is no vague. You either intend to stay together and it is a marriage or you do not intend to stay together and it is fornication. And, yes, i'm intentionally ignoring the whole sex = marriage debate.