My (m/25) bf avoids opening my (f/30) msgs at work. His reasoning is that I’ll feel ignored if he leaves me on read and is doing it that way for my sake. But isn’t ignoring opening my msgs the same thing? Should I feel so offended?

My bf of 4 years told me he loves when I (f/30) visit him at work with coffee. So I went there today and sent a pic of the coffee I bought him. I sent another msg and told him I was there with coffee if he wanted to come out and grab it. (I’ve only visited once before and he made out like he wanted me to do so more, and I only drop and go, never linger) I watched him go out to get a drink of water, look at his phone for 2 mins then go back inside. He never opened my msg. He’s seen a preview and knew I’d messaged but didn’t see what I wrote because he never bothered to open it. I ended up leaving without giving him the coffee. Now I understand not being able to reply at work… But if you have time to look at anything on your phone for 2 minutes, wouldn’t you look at your gf’s msgs? He says he won’t open them incase he needs time to reply and doesn’t want to leave me on read because then that’s ignoring me. I feel like not opening my message at all when you know it’s there is also ignoring me, just more slyly. I don’t feel very good about this. I get excited at work when he texts, it makes my day. I try read them at the copy machine when I have maybe 10 seconds time away from a customer, even if I can’t reply. If he was so busy why is he even looking through his phone at all? I just feel like he’s not that interested in me sometimes. Please help- is this an indication of lack of interest?