If he talks about history a lot or likes buying historical items, I think the crush will perceive that he's interested in that, even if he never says it. But if he never says it, the crush may also call him out on it just to tease him.
I found some other books about writing character emotion or scenes with emotional impact if it's something you want to read up on more. These books cost about $15 each, the cheapest shipping option that is. Not sure if you want MORE of that sort of reading material but just thought eh, why not.
https://www.amazon.com/Writers-Character-Emotion-Fiction-Writing-ebook/dp/B00IQDW81W
https://www.amazon.com/Writing-Emotional-Impact-Techniques-Fascinate/dp/1595940286