sitting on the aeroplane waiting to fly home 7:30 pm I glanced at partners phone & he was WhatsAppin a women I had never heard him mention before. A little bit of digging it turns out she works on his recep at work, and is newish 9m. At the wkend we were laughing about lengths of texts MvF and as he was showing me his bloke ones & I saw her in his WhatsApp again. We both have M&F friends through work etc and he often chats about other F in his office but not this one. I went through his FB posts and I see strarting in December her hearting his posts and the whole time we were away too. Other women he knows do this but I know them or know of them. Around December I found his behaviour to be rude and thoughtless. On more than one occasion he has said he has told me things that he hasn’t so who has he told. I really want to ask him who she & what is going on given these activities with no mention of her ever.. we don’t live together and are both independent with lots of time to pursue our hobbies work etc up until now I never considered he would stray I am being silly or is this a red flag....