He said it's because I am probably coming over for a few days when I can, to meet him, and he wants the children to know beforehand. He said they were fine with it, although I thought they might mind, and somehow don't mind my age.

Well it's tricky meeting young men, I am a bit old fashioned so would prefer to meet them in real life, but everyone these days seems to meet online on a dating site. Except a few who have tons of friends and meet them through friends. Just out of interest, how would you suggest I meet them? Nights out haven't proved productive ... there are also no Meetup and similar groups where I live.
Thank you for your comment.