Lost and heartbroken

Is it normal for your partner of 8 years to suddenly not want to sleep with you(sexually or just in the same bed). Lately I’ve been having to ask my partner to come to get into bed with me. I’ve been trying to have sex with him and there is always ad excuse. He is always taking his phone and hides it from me and also he literally gets mad if I say “hey let’s just walk the dog together” which is something we normally would do together. I’ve been feeling so alone and idk what to do. I don’t want to just give up on the relationship but I also feel like he has lost feelings. Any advice or anything….