Should I feel guilty? HELP PLEASE ⚠️⚠️⚠️

I've been talking to this guy for a while (about 5 months) and we're together but we're not exclusive. He and I have passed the I love you stage and everything but lately he hasn't had as much time for me as he use to because he says he's going through a lot so I understand that but he won't talk to me about it and I was ok with that but I would ask how his day was and he would say bad or not so great and wouldn't tell me why or how he feels and I'm always trying to remind him how much I love and care about him but I don't feel like I get the same attention and affection that I give to him and when I ask him to define the relationship he always says we're single but I'm his and he's mine but I have a hard time believing that we're together but he doesn't want to commit and I asked again a couple of months later and he had the same response he rarely calls or text me anymore he doesn't go out of his way to make me laugh like he use to or even just call to say hey beautiful 😔... anyway one night my friend who(calls and text me more than him) I've know for a while and I were hanging out and one thing led to another and we slept together but it was the best sex I've ever had for some reason I feel bad because I was thinking about my guy but then again I don't because he ignores me like he isn't scared to lose me so should I feel guilty for this or not.