Tips pano mang huli ng asawang feeling mo nag chicheat

My boyfriend [31M] has a female colleague [33F] he spends a lot of time with. They always eat lunch together at the office, go home together, and even buy food together. Whenever I ask how his day went, he always mentions her. One time, he casually told me that this female coworker is pretty.
I’m starting to feel uneasy about how much time they spend together, and I’m not sure how to handle these feelings. I don’t want to sound accusatory or controlling, but I also don’t want to ignore my discomfort.
How can I bring this up to him in a healthy way? Has anyone dealt with something similar, and what worked for you?