Some people form sentimental attachments to possessions. Some people don't. Some people form sentimental attachments to all sorte of things though: football teams, songs, artworks... I've never really seen this as a "problem" that needs addressing- I'm not sentimental about inaminate objects, that's just how I am. In fact, in some cultures, the ability to not place too much value on tangible objects is seen as something to aspire to.
Seems to me that's all vastly different from the dissociative issue of thinking that things actually cease to physically exist if you can't see them. But then, that doesn't seem to be the issue you're describing.
And then there's the attachment anxiety you're describing with your T. Human relationships and our healthy/unhealthy attachment to them is vastly different to our ability to get sentimental over objects. And IMO, this is an important issue. I have attachment issues with people, and unlike my attachment issues with objects (which is totally a non-issue for me!), it does cause dysfunction in my life, as well as significant amounts of distress... for what it's worth!
