By the way, I mentioned senior people thinking you are gullible. I thought I'd spell out why.
he feels the same BUT he is 15 yrs older than me and has written himself off having a relationship and doesn't want to go through it all at work
There is no one I can talk to about this
He hasn't told HR then? Not asked for one of you to move team/office etc? You are keeping it a secret from your friends and your colleagues?
He has told you he doesn't want a proper relationship. He loves you of course but he just can't have a relationship because he is kind of troubled in some way.
All of that is such a cliche, I am now wondering if you are a journalist looking for a story. If not, he is a sleaze ball who is using you for illicit sex and ego-stroking, not a bloke who happened to fall in love with someone at work.
There's a reason older professional men get into these situations with much younger women at work. I bet you think he's brilliant. I bet you think you are lucky. I bet he shows you the most amazing things that really impress you: nice wines, fancy restaurants, knowledge of the world, good sex, smooth ways. Do you think he might actually be your soul mate?
The women his age won't touch him. They see him for the sleaze ball he is.
Is he divorced?
For god's sake move on. In 15 years time you might do a little sick in your mouth when you think back on how you were groomed by a sad wanker who needed his ego stroking.