He fancied one of his teachers in college. It seems she fancied him too. As soon as he started he said they always got on well. He was 18 and she was about 34ish. She ended up being his personal tutor and he was in a gifted and talented group and she worked with him in that. She gave him lifts sometimes after evening classes. He went to her house several times for extra tuition and he swears they didn't even kiss but they hugged. They sent cards to each other and gifts, she gave him some Jo Malone, this is back in the late 2000s. They also kept in touch when he went to university but it fizzled. The last he heard was her calling him out on LinkedIn for ghosting her about 10 years ago.
He's 37 now and married and his wife is due to give birth to their first child in the next few days. He's never told my SIL about this or our parents but I knew at the time. He'd spend loads of time with headphones on playing music and staring into space. He keeps ruminating on it and talking about it and it's concerning.
I don't know what to do just ignore it? I'm hoping when the baby arrives we'll all be so wrapped up in that it'll fade away.