As taxi driver says, your stay over 6 months may not harm your I-130 Petition (presumably for your wife since you have green-card). But repeated stay of more than 6 months outside US will raise some questions at Immigration and he can refer your case to the Immigration court as your intent to give up your permanent residency status. As for the USCIS case status, since you are a GC holder, your relatives doesn't qualify as Immediate Relatives (IR catefory) which has unlimited visas available at any given time. It means the numerical quota for Nepal for the category has been fulfilled for the year. You will have to wait for the next quota.