helping for a friend

ok so one of my friends thinks there girl best friend likes their boyfriend. i know what she's going through bc i felt the same, i went past it after reasurince but i dont know to help her, shes asked the girl best friend is she likes him but she has said no. the boyfriend has said he has no feelings for her and sees her only as a friend but my friend doesnt know if its true and to believe them. should i just tell her to have a talk with the 3 of them and clear it up and move past it or what? i want to help her the best i can but i dont really know how to since we are 2 different people. my friend has been going through past messages with me to see if we can find hints of flirting or anything just as proof but i dont know if that will help bc she might lie to my friend. i need help bc i dont want my friend to be heartbroken if her bf leave her for her girl best friend or she gets cheated on.