There were no "no-fault" divorces until recently. If a new-boyfriend and new-girlfriend cannot show discipline and self-restraint in the first few months of their relationship, it shows they are not mature enough for marriage.
I would hand them Benedict's new encyclical on love and have them read it together. Ask questions and discuss it with them. If they appear to be devoted to living a marriage of true Christian love, then I'd ok the marriage.
They have to mature a bit. The girlfriend deciding not to kill her child and the boyfriend willing to raise the child is a good start. However, it is only a beginning. They need continue their growth in maturity.
Coercion, fear and force can all invalidate a marriage, because it has to be undertaken freely.
I don't get the sense that the priest "refused" to marry them under any circumstances, though, especially if you look at what the teacher says about it.
That's just unwarranted hyperbole by a clearly biased writer.
You only have the fornicator's word that his marriage was refused because the priest thought they didn't love each other. The social need to legitimate a pregnancy can be considered the psychological equivalent of a "shotgun wedding." The duress involved could possibly be grounds for nullifying any marriage. I'm no canon lawyer, but it looks like he and his girlfriend could very well be impeded from contracting a valid marriage.