It's a statement of approval. It depends how serious the relationship is - but yes, it could mean marriage. Or even just a date!

Worthy and deserve are very similar but deserve also implies entitlement. So, although, I may think someone is good enough "worthy" of my daughter, I do not think anyone is entitled to "deserves" her.

You usually hear it, "You are not worthy of my daughter." It is usually associated with marriage. It is discussing more than a casual relationship as a general rule. Or it could just mean, the dad really likes the guy. I have never heard it used in the positive like you used it though.

I think You can translate it this way.