Being a good friend ?!?

Ok well , I have a friend that has been dating her boyfriend for over a year but clearly he's not making her happy anymore .. She's 16 & he's 18 & she has a lot more ambition then he does even though I realize at the end of the day it's up to her but I just don't see the point of holding on or trying to force a relationship if you're not genuinely happy & putting in the most effort for it too work . I get the fact that when you're in love it's hard too leave & move one but I think sometimes you have to just do what's best .....