If the father or daughter refuses, he obviously cannot actually do it. He is still obliged to pay the bride-price, however that part is difficult to interpret into a modern context.
Does it make any difference to us who the guilt falls upon? God will judge correctly. We don't actually need to know the answer to that question.
The practical implication of all this is very clear: Don't "have sex before marriage", or more accurately, don't have sex when you are not committed for life. Because if you do, and don't follow through and turn it into a marriage, you're in sin and are opening a whole complicated can of worms. Instead, make sure the two of you are committed for life, ideally formalising this (a wedding is a very good tradition as it gives marriage the seriousness that it needs to have), and only then have sex. If you do fall into temptation and have sex prior to making such a commitment, then go and make the commitment, make it permanent.
Incidentally, the practical implication is essentially identical whether you look at this in the way
@The Revolting Man does, or the way I do. So really, it doesn't actually matter much which view is technically correct, as the practical result of either viewpoint is identical.
There is no obligation to attempt marriage for non-virgins - whether or not she's a believer. However, given how strongly marriage is encouraged throughout scripture, and knowing God's general attitude towards men and women, it is obvious that it would be the right thing to do in either case. It's not a matter of avoiding sin, it's a matter of understanding God's heart. Seeking to do what is positive and good rather than just seeking to avoid what is negative.