Commitment issues? Intimacy issues? Puberty?
Since you didn't mention age it's harder to give meaningful advice. And experience, which I have to take as 'inexperienced' or she wouldn't be having this problem.
She'll need to step back and take a deep breath and try to realize she needs to allow a little trust into her life. If she's afraid of being hurt. That's my prognosis on the info you've given.
We all go through trying to make sense of our feelings and experiment.. use what works to the best advantage and discard what doesn't work, but not giving love or a relationship a chance to develop will leave you always posting on &totse for advice.
As for your role, support your friend and look out for her but keep your distance when she sticks her foot in the water. Be there if needed but back off if the situation warrants.
