Hi frnds

I am in love with girl, she is of other religion, in our relation of 2.5 yrs, I have caught him 2times with other guys.
With one he was flirting & with other ( who lives in same appartment of her) she was in just attachment as he use to teach her.
1.After I caught her second time, I am just confused whether shall i keep our relationship or shall i part.
2. I have also experienced that our relationship from her side is not deep as it was earlier. May be it is of same dept but she always tries to avoid our secret meets.
What should i do

(Screen) Name: PC