What would you do if your best friends are sacrificing their love for you?

I wonder how do you use the word "SACRIFICE" here ... does it mean that ... he or she is already in a relationship with some person or something... here also what is important to understand is that what does that person feel about you... i mean the person for whom both you best buddies have fallen for... her/his opinion matters the most... you guys/gals have to clear this doubt with that person first... and convey your messages to him/her before you start fighting for rights over him/her