Am I overreacting or is my husband’s behavior unreasonable?

I need some help figuring out whether I'm going crazy or if my feelings are valid. I apologize in advance for the long post. Here's the situation:

My husband (m33) and I (w33) have been married for six months, but we've been in a relationship for 7 years. Every time (and I mean every time) I grab his phone, he asks, “What do you need it for?” “What are you doing?” “Why do you need my phone? Why can't you just do it on your own phone?” It’s so annoying that I honestly try to avoid using his phone altogether. Rather than getting into long explanations, which I hope would be convincing enough for him and prevent further questioning, I just find another way to get whatever I need from his phone. On the other hand, whenever he takes my phone, I don’t ask him anything. If he asks for it, I just give it to him without comment.

That being said, I’ve brought this up to him a few times, mentioning that it bothers me and feels a little suspicious when he stands right next to me and watches me over my shoulder while I use his phone. It doesn’t always happen, but for example, after I finish watching an Instagram Reel, he’ll immediately ask for his phone back and refer to mine. I trust my husband 100%. He’s never given me any reason to doubt him or worry about infidelity.

Last night, we were getting ready for bed. He was faster than me and had already changed clothes while I was still filling the dishwasher. I was walking around the apartment, checking if there were any glasses or cups lying around. I passed by his office and went in for a moment to check if anything was left on his desk. I turned off the light and left. As I was walking out, I heard him ask, “What are you doing in my office?” I said, “Nothing.” He responded, “But you just went in there. Why?” I said, “I was looking for dishes.” His questions kind of triggered me. It wasn’t just about his phone anymore – now he was questioning why I’d quickly stepped into his office for 20 seconds.

I didn’t want to make a big deal out of it, especially since we were about to go to bed and he had to work the next day, but after I gave him a half-hearted goodnight kiss, he noticed my mood had shifted. He asked what was wrong. After a bit of hesitation, I calmly told him that even though I trust him, his constant questioning and looking over my shoulder when I use his phone or briefly enter his office makes me feel like there’s growing suspicion and secrecy. I wanted him to understand the impact this behavior was having on me.

He brushed it off at first, saying he was only trying to help me. He claimed he just wanted to make things easier for me, so I wouldn’t have to search too long in his office or on his phone. He said it was normal for him to be curious about what I was doing with his things. I should note that he’s generally not a curious person in other areas of his life – I’m the more curious one.

I tried to stay calm, but he started getting louder and louder, accusing me of being insecure and told me I should work on my insecurities. He even insisted that I take his phone and check it if I wanted, offering me all his passwords because he has “nothing to hide.” I told him I had no desire to go through his phone or his office; I just wanted him to stop asking questions and watching me. But by then, he was already so upset, accusing me of making “underhanded” accusations. After I asked him three times to drop it, he didn’t, so I left the room and went to lie down on the couch in my office.

About 15 minutes later, he came into my office demanding that we talk. He kept repeating his earlier accusations, only louder, saying that I was insecure. After calmly addressing his points again, I realized I was reaching my breaking point and asked him to leave the room. He did, but not before turning on the brightest light and slamming the door behind him.

I can’t shake the feeling that there was some gaslighting going on here. He denied everything, saying I was the one with the problem, even though I had expressed my feelings calmly and rationally, asking him to stop certain behaviors. He refuses to see things from my perspective and insists he’s completely right in questioning me, and if it causes me any discomfort, I’m the one who needs to deal with it.

There are a couple of things worth noting: First, he’s at work right now, and if I wanted to, I could easily go into his home office and go through everything without him noticing. He leaves his phone in other rooms or forgets it when he walks the dog, so I have plenty of opportunities if I wanted to check. I also know his passcode. Second, we recently had a situation where we were both watching Instagram Reels on his phone, and every 2-3 Reels had half-naked women in them. I mentioned that it was a bit weird, and I stopped watching after a while. Later, when he returned from walking the dog, I calmly mentioned again that I found it odd that every few Reels featured women like that. He said he didn’t understand it either, and that it wasn’t something he actively searched for, but it’s just what the algorithm shows him. I asked if I could look at his Instagram, and he immediately agreed and handed me his phone, but again, he hovered over me while I looked through it. After browsing his feed, I saw that it wasn’t nearly as many women as the Reels suggested. I also did some research on Reddit and found that it’s common for men to get these kinds of Reels if they follow or like “male” interests. Anyway, I gave him back his phone, and we left it at that.

So, my question is:
Am I being unreasonable in asking him to stop questioning me so much?
And do I have a right to feel like his reaction is a form of gaslighting?