What do I do with this?

Well, talking with her is more likely to help you both resolve it.

It might be that both of your lives have a lot more busy-ness and richness beyond your friendship, which is good.

But perhaps your sensitivity has uncovered depression in your friend. I would have a good talk with her to try to ferret that out.

If it's one sided in any friendship or relationship you's up get very bitter and resentful especially if your leaving it happen .
No.1 it destroys your self worth .
No.2 you said it you feel empty .
See in relationships when you pick up energies off one an one at times the energies you pick up is that there's something going on what you don't wanna look at .
That's one form of energy cause I tell you here right now and I'm trying not to hurt you , energies isn't love . It's the opposite. It's fear .
I can relate to you cause all of that happened me that's why I can explain .
Do you know where my energies led me into with friendships and relationships ( a psyche ward )
That's where energies lead you too .
I can also explain about meditations that they teach about energies . It's all to too take you away from God .
That's another part of energies my friend .
Of course energies pick up at the start of a relationship when your nervous getting to know one an other but not a long term friendship or relationship

That's sad. Friends are important. Having someone to connect with on a higher, deeper level is magic ✨

So it lost the chemistry? That happens sometimes. You're not a bad person or a bad friend.

As for how to handle it, someone smarter than me will have to jump in there. I just wanted you to know it's okay.