It's a very hard decision. Lose your loved one or someone else loses their resources. I'll personally go with the former, not because I hate Nagi, but I think it's more important. If you truly love someone, be with them. Don't lose them for other's sake. And with Nagi's contacts being rich, I'm sure she can manage. Love is a once in a lifetime offer. Decline and you'll lose it forever. It's incredibly rare to get a second chance. Nagi will get her second chance in life but Hayate won't.
I don't know. Knowing Hayate, he'll probably find a way to do both.