T.F.
If she wants advice from you, she'll ask for it. Otherwise... back off... be available to her at ANY time and make sure she knows you are there for her to support her.
It's normal for girls this age to back away from mom. Don't be pushy but try to initiate some things for you 2 to do together.
My daughter, 23, and I are tight as a mother/daughter and we are each other's rock. It was not that way at age 15. We never went through hard times but it was emotional many times with me feeling left out of her life. I just stayed the course and it worked out.
We get mani/pedis monthly and it's "our" time. We treasure our spa day with each other. We also enjoy each other's company.
Hang in there... support your girl and let her come to you.
I will say I think she's too young to be this involved in a relationship. Does she have extracurricular activity? My daughter's cheer kept her calendar full with training and volunteering.