Seperation anxiety

Anyone’s little one developed separation anxiety at 6mo?

We don’t live near family, so have only left our daughter with trusted friends a few times (probably once a month). She had been fine up until now. Then the last two times I left she has screamed the house down the whole 30-40mins I was away. This is not the first time she has been babysat by these friends, so I don’t think it is a stranger thing. Once I come back she calms down immediately and even laughs and smiles at the babysitters.

How can I break her of this? I feel bad leaving her with our friends for even 30mins now...but I also need a little break every now and then!