Need opinions please

Ok so I know that this is all going to sound so childish and stupid but just hear me out because I have no one else to ask. And I’m sorry it’s so long but I needed do get this off my chest. I have no one to talk to. I have just started working at a new job where I met this boy, let’s call him Fred. Fred had a gf when we met but a week later she broke up with him and then we started getting close. He asked me if I’d go out to dinner with him to which I agreed and ever since that first date we’ve been inseparable. We see each other at work and when we’re not at work we like to go out. But we’re not an official thing and when people ask him, he tells them that we’re “talking”? Mind you, it’s only been a month since we’ve met. But already I feel so close to him and feel like I’ve known him all my life. I feel comfortable around him and I can be myself. So, we had sex. And since then it’s not the same anymore. Yesterday was his grandfathers one year death anniversary and he didn’t call or text all day. He had told me he wanted to go see his grandfather because he hadn’t gone since the burial. He said he hadn’t felt emotionally prepared but he felt like he was ready now. I didn’t call or text him either because I wanted to give him space and time. Then at the end of the day, he texted me saying how could I have not texted or called all day. I explained why and he said he didn’t feel important to anyone and that he didn’t know what we “were” exactly. I really like him and don’t want to lose him over something so stupid like not texting him all day. I guess what I’m asking is what do I do? I don’t even know what I’m asking, I just needed to get it off my chest.