AITA: Visiting a prostitute without my gf knowing

I'm in a 10 year relationship with my now fiancee my first serious relationship, (previous relationships didn't even hit off beyond first base) however before actually tying the knot I'm curious about sex with other people. So I'm intending to go on a solo trip and visit an escort, when she's on a family vacation.

We did talk about an open relationship but she told me that she's not ready for one yet, and foresees that it would be relatively late into our relationship before exploring on kinks other than vanilla sex.