My sister has been with her fiancé for 5 years and it was all great until she started a new job. Shes got close to her boss and she talks about him a lot and they have 'banter'. You can tell it annoys her partner but he trusts her completely. My sister and I are very close and I know when she is lying and something is up. There have been work meetings that have run over and random shopping trips out alone. I just feel in my gut that something is 'off'. How do i catch her? Or do i just stay out of it completely? Her partner is a good man so i feel bad for him if there is something going on.