Not necessarily.

Case in point. I tend to lock my phone not because I have anything questionable to hide but because experience tells me that partners can be nosy and as I alluded to earlier, can take the most innocuous comments or texts out of context and turn them into a reason to distrust or question you.

Some people might note that expecting full openness with personal devices is driven by past experience in being deceived and this is true but rarely do people think about the opposite where one person in a relationship has experienced being unfairly treated with regards to having been given no privacy in the past so affects our need to be ever more vigilant going forward about our privacy.

When you're with someone for many years that is excessively jealous and has a suspiciousness streak in them you tend to be more protective of your information too.

Keep this in mind and maybe have a conversation about it to understand why he values his privacy so much. on top of my opinion being that it's like one of the last places we have left to actually keep our private information anymore.. it may be something related to that.