Blocking and cheating…

My husband and I have iPhones so when someone blocks you it shows that message wasn’t delivered and you can’t call them…so he deliberately downloaded a blocking app…just so he could block my phone from calling him, but I could still send messages. Obviously so that when he’s with another woman, I can’t call…but he wants me to still be able to message him so it’s not obvious that he blocked me and he can still communicate….that’s a theory…tell me now…is there any other reason why he would block my number like that while he was out?? I wasn’t texting or harassing him at all….