I am planni
Universities do not issue official invitation letters for something like graduation events. At best, they will only confirm that such an event is taking place, and that you are a member of the graduating class. They will not write anything stating that your attendance is required. They can send you your diploma in the mail.
Your "girlfriend's" family is highly unlikely to go through the hassle and financial risk of getting an official invitation for you.
The consul is not stupid, and will see right away that the real reason you are coming to Poland is to stay and seek work. Since he cannot determine that you will return to your own country when the visa expires, he will probably deny your visa on those grounds. You cannot demonstrate that you have strong ties to your own country.
I think you are wasting your time and money. Work a few years in India to get experience, then apply for a job in the EU. Forget about the "girlfriend".
