Honestly I don't have a clue about this. But I noticed no one had replied to your post. So I thought I would.

Clearly, there's no way for me to know what might be going on in your friend-of-a-friend's head. Given the difference in your ages, though, perhaps in reality he saw this encounter simply as a good opportunity for a one-night stand &, now that he's had it, he just isn't interested anymore? It's possible though that, sooner or later, you may hear from him again sometime when he's horney.

I would suggest not texting him too much. I could see where a guy who's 45 could easily be intimidated by being repeatedly texted by a 25 year old woman he had a one-night stand with. It could well scare him because even though you say you're not interested in a relationship, your constant texting may suggest otherwise to him. Besides, who knows what else he may have going on in his life that your texts could compromise? Personally, my thinking would be to just move on & not pursue him since you're not interested in a relationship anyway.