a block glitch?

so about a month or two ago one of my friends on Xbox live suddenly just appears offline, but
only to me, not to any of my friends, when we are in parties i can't hear him, and he cant hear me, but if anybody else is in a party they can hear him just fine, and when we are playing Minecraft, even when he uses chat i cant see it but everyone
else can. he's not blocked me, and all my other friends are not having a problem with his account. i have privacy settings off, and he can still message me, but nothing else. is it only me? or is it a glitch? also how do i fix it?

:)