Ok, here we go:
About your first rabbit, building a newst: As always, you should consult a vet, as this is a medical matter, but it does sound a lot like a False pregnacny
It basically makes your doe act as if she was pregnant, even if she is not. It it can even happen for females that are kept alone, but nearness of a buck, mating that does not cause actual pregnancy and basically anything that the does body interprets as sexual activity can promote it happening. It usually passes all by itself, but if it doesn't, you will need to check with your vet what he suggests.
About the second rabbit: Sometimes, rabbits just don't want to mate. It happens, possibly especially in pet-breeds (I have no sources that compare the willingness to mate between wild, domestic and pet rabbits, so it just is reported more and more openly for pet breeds).
Sometimes, the time of the year, the weather, the temperature, everythign that would affect our mood as well, may be an influence, but that could be anecdotical as well. But you may want to keep an eye on that second doe as well. If it shoes an otehr unusualy behavior, have a vet check her over. I woudl think it unlikely she's got a medical problem, though; just a mood-one.