Bf probs

So My bf  & I we have been getting serious with our relationship and he met my dad and everything and we are looking into marriage for our future plans and the communication is great between us. Except lately he hasn't been communicating often with me. Last time I saw him was a week ago, and the last time I talked to him was more than a week ago, and when I texted him to make sure everything was okay, and all he could say was "he was stressing" but that wasn't enough for me. Should I be concerned or what? I already tried reaching out and I don't want to be that attached gf that constantly texts him bc he's not giving me attention but it's not that it's just it's not normal for him to act like this and it's very strange for me. Any thoughts? Advice?