My partner felt I interrogate him about his night out but why shouldn’t I ask?

My partner of 8yrs went to NYC on a business trip. He booked a “party” style hotel which dismayed me. But I understand it’s only reasonable to enjoy your time at NYC as well as work. We mutually agreed I could check in on him ANY time or he would update me on his night outs.

On Friday night (mid-night there time) I didn’t see any txts from him so I txted : how was the night. He replied he was at a bar with friends so I said yeah sent me some picture! He sent me 4 pitch dark images no one could tell what the hell they were. I asked what they were? He replied quite surprisingly aggressive: “I’m doing my best stop stress me out”.

Do you guys feel I interrogate too much or he was overacting. Have I done sth so offensive?
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Hey guys thanks for the answers. The reason I would check in is b/c he went to strip joints even prostitutes in the name of business in the past when I was completely unsuspicious. I think I should dump him rather than living a scared life.
My partner felt I interrogate him about his night out but why shouldn’t I ask?
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