Bizarrely this didn't fall into place with me at the time, it was months later, I ran into the person involved and demanded to know the truth.
I had been in a nasty accident and was on crutches so ordered a taxi home from work. The taxi driver was full of chat and when he heard the complex I was heading to informed me he had dropped a sex worker to that same complex. It was on a public holiday and he has waited to collect her. He wasn't sure about waiting but she had begged him. She paid obviously but he said he felt so sorry for her. She was young, seemed very naive and nervous. When she came out she was quiet and seemed upset. She said it was fine, he was fine if a bit weird. The driver felt concerned about her, having to make a living like this. He dropped her home for free. She was crying when she got out of the car.
We don't live in the UK by the way. I had never heard of a sex worker being ordered. I was shocked. I commented I was in hospital that day having surgery and asked which building had he dropped her to. Lo and behold it was the building I lived in. Even stranger. I knew or knew of everyone in my building, all young couples like us, all seemed nice enough. It was in the middle of the name. I felt sorry for whoever the girlfriend was, oblivious to this going on when she was presumably at work. When I was in hospital myself and boyfriend had had a huge argument, he had been acting really really strangely on the phone and then accused me of being crazy on medication when I asked him what was going on. He barely visited me and had to be practically bullied into collecting me and had barely said a word. I had enough to deal with with my rehab and had kinda forgotten the weirdness.
Still the penny didn't drop. Even when the driver helped me with my bags then when he realised the front door we were headed to balked then asked if the door lead into multiple apartments, got completely flustered, backed away mid sentence and practically ran to his car. Even then the penny didn't drop.
I wondered what had caused his abrupt departure and briefly wondered did he think I was trying to lure him in the door because we had been chatting and laughing so energetically as he was helping me up the steps. But it seemed totally unfeasible.
When my boyfriend arrived home I told him the shocking story I'd heard about one of the men in the apartment block. There was nothing noteworthy about his reaction.
Ages later when I discovered what a massively deceptive gaslighting manipulator he was and dumped him, I got a sudden flashback of the driver recoiling in horror at my front door. The next time he picked me up (I used his cab company quite a lot) I demanded the truth and sure enough he had told me a story about my own apartment. He described the guy who came to the door, it was definitely my ex so couldn't even be explained away by a friend borrowing the apartment.