Black and purple?

I recently caught a glimpse of my gf chatting on her phone and wanted some help figuring out what she was using. I think it was an ai/chatbot because the responses came so quickly, but it was a chat with a black background, white text, and purple chat bubbles for the messages she was sending. There were also four pictures of a man’s face in a grid pattern, but I didn’t get a good look. I wouldn’t mind if she didn’t have a history of cheating, but I find it hard to trust her now.