Thank you for clarifying the situation.
If your wife has an unlimited residence permit then it’s a so-called Niederlassungserlaubnis (=settlement permit). That entitles her to bring her core family (husband and children) to Germany.
It’s not unusual that Ausländerbehörde (the German aliens department) issues your residence permit for just one year first. They put you under general suspicion that you just got married in order to get a better legal status. So what they do, is to check after one year if you are still living together. Then you usually get a residence permit that is valid for two years (and then a settlement permit after these two years).
It’s in the nature of things that a residence permit grants you more rights than subsidiary protection (for example you are allowed to move to Germany). The downside of it is its much shorter period of validity and that you have to renew it after one year.
Concerning the effects of your German residence permit on your subsidiary protection status in Italy: Italy granted you subsidiary protection because your home country was not able/willing to do so. Getting a residence permit in Germany basically shows Italian authorities that you don’t need their protection anymore. That’s why I assume that your subsidiary protection status expires as soon as they find out about your legal status in Germany.