My DH is overly concerned about his colleague

[Yiu124]

My DH works in a stressful job. He often comes home offloading. He has a few peers at work he’s friendly enough, but lately, he’s become overly invested in his female peer work stresses. They are in stressful situations- I get it, and they offload. But they are chatting a lot. She checks some of his essential emails. I often overhear him telling her to look after herself, that he’s concerned about her, not to work late, and that she cheers him up. Is this normal? Corporate environment for context

Again, you cannot know what they are thinking about you

Yes, he might be. It's called friendship. Men can be friends. It can be balding 50-something Brian from Accounts. It's just that you wouldn't be concerned about that because it doesn't threaten your relationship.

Oh I'm 100% sure! He has a very beautiful.girlfrirnd 20 years younger than me and he's very open about how he feels about her.
He's a guy who is very sensitive and generally doesn't enjoy the company of men.

All of the above can be true and still... You can't know what he feels for you.

You seem very focused on this - perhaps you can't have platonic friendships but others can. And it can be very clear cut.

I just know of several women who would have sworn blind they were having a platonic friendship / brother/sister relationship/ close colleagues only relationship over years or even decades, who then learned that their friend had had the hots for them over all that time.

I'm not saying it always happens. I'm not even saying it's a terrible thing (one confessed after the marriage broke up and they are now together). But I am saying you cannot know.