confrontation ≠ conflict!

I don't get people sometimes... I have a friend that I signed up for a class with and we have been carpooling...until recently! She hasn't felt like going to class which is fine with me, BUT instead of telling me that she is not going, she just drops off the face of the earth for a while and doesn't answer her phone... Frustrating! I guess I will never understand why people do that. Am I that scary? Do people feel intimidated to tell me how they feel? It just ends up being a way bigger deal for me cause I feel avoided and that irritates me. Plus I feel like it is such a selfish way to deal with things! It is difficult for me to relate to somone who is so anti-confrontational, because I am soooo not! Sure it sucks if you feel like you what your saying is letting someone down... but ignoring them doesn't bother them at all? Seriously!!? Purhaps I am over-reacting, but purhaps not...