When someone starts flat out ignoring you

A long distance aquantince of mine has started to ignore me. I'll comment on her posts and she will reply to others but not myself (within the same time frame as others). I've noticed this over the last couple of months.

I cant think of anything I could of done to offend her.

After months of this...

What would you do/assume?

I dont want to confront her, its not THAT serious and I truly hate confrontation. I'm just curious what others would do in this situation if you didn't want to confront them either.