Friends problems?

ok, so, i thinkg my best friend might be mad at me, we havent really been talking as much as we used to and when we do we pretty much only talk on yahoo messenger, but we use small talk, such as, yes, no, uh hu, ... and stuff like that, and i just resently found out that she had a boyfriend, she didnt even tell me, i found out about it when i was looking on her yahoo answers page, what could this mean? what can i do to find out if shes mad at me?