My husband loves me but clearly fancies a woman at work. How can I manage my jealousy?

‘Attraction is so much to do with possibility, with what we don’t know, that someone comparatively unknown can be a real magnet for the imagination.’ Painting: Between Two Fires by Francis Davis Millet. Photograph: Heritage Image Partnership/Alamy

My husband and I work together in a large business. He clearly fancies a woman there – I can tell by how he watches her. He brings her up in conversation and says he feels sorry for her, as her husband doesn’t treat her the way he treats me. She isn’t in a bad marriage at all, it’s just his opinion.

I broached the subject with him as it was upsetting and humiliating me at work. He laughed at the idea and says I’m the only one for him, but I know by how he reacted that he isn’t being honest.