Passcode 🤔🤔🤔

So my partner of going on 8 years recently brought a new phone which never had a password. Since owning this new phone, now has a passcode🤔 he told me what it was however I can't shake that it's odd to do so with the excuse of "well if I loose it it's secure" like mate you haven't lost a phone in the 8 years we've been together🤔🤔🤔 am I overthinking💭💭💭 or is this valid. Seeing as though I'm petty I'm thinking of adding a passcode to my phone then when he asks why just saying " it's secure for if I loose it" 🙈

Not to mention when I did use his phone there's all types of pornish things on there which I'm not thrilled about, he knows how I feel but doesn't care enough to change it as it's apparently "what all guys do"😞

EDIT- thankyou for opening my eyes up. But yes there has been major trust broken in the past💔 ($$$$ spent on camgirls/camchat) so yes it's difficult to not overthink the small things especially cause he rarely leaves his phone even on a bench. Always in his hand, pocket. Doesn't even leave it on the lounge chair arm when he's messaging back and fourth with people. Hand...pocket...hand...pocket....