I've changed my name for this as I'm sure my DC know my usual username!
Maybe emeshment (in the title) isn't the right word but I'm not sure what is.
I have two DDs - 20 and 18 - and the level involvement/emeshment that seems to occur in teenage relationships really concerns me.
Dd2 has been with her boyfriend about 9 months. He has her bank card on his googlepay, and she has his. They both use them and see their money as "our money". They both have access to all of each others social media accounts (and check them regularly and often take screenshots) and have each others phone PIN. She often gives him her key to our house to let himself in. I've objected and she says I'm weird - she also often has his key to his (parents) house and apparently they don't mind (though maybe they don't know).
My older DD was the same in her relationships (she's currently single) and all their friends are exactly the same. When I voice concerns about giving a boyfriend of a couple of months access to your bank account/social media and having access to theirs, they all (their friends included) tell me I'm strange and old-fashioned and that if a boyfriend didn't want this kind of access or give them this kind of access then they would question his commitment and leave him. They see this as some sort of feminist standpoint.
It also seems to be commonplace to not "allow" opposite sex friendships. My DD has a "good" male friend who every time he gets a new girlfriend blocks my DD on all social media. My dd gets slightly upset each time but it seems to be accepted. It happens to all their friends as well, and when the girls get a new boyfriend they all go through his social media - which of course they have access to - and block all female friends. When they split up, female friends get added back. When I've spoken to my DDs and their friends about my concerns about this they just say times have changed and its a matter of respect (ie not allowing a girlfriend to block female friends is seen as disrespectful)
My best lives at the opposite side of the country and has DDs the same age. Its the same there too so not an odd local thing (though she didn't know it was until I talked to her about it and she asked probing questions - when we first spoke about it she believed nothing like this happened with her DDs and their friends).
Am I being unreasonable to find this level of involvement/emeshment scary?