Would sending a message to a friend with benefits be considered a violation of privacy?

[Rodney]

So my friend with benefits changed her number and said she would contact me later in the day and didn't. I am thinking of asking her what happened over facebook would that be a violation of privacy? It is possible she changed her number because of me but she never had said anything negative to me i'd imagine if she hated me she would tell me that after changing her number rather than tell me "Oh sorry changed my number i'll give you new one later."