This is exactly what every person walks around with that is not spiritually cleansing regularly, including themselves, their homes, their vehicles and their work space. Attachments can form in many ways. They can be sent by enemies, they can be from birth, they can be from the company we keep, they definitely come from sexual interactions. But even with something as simple as a hug or handshake you can pick up someone else's attachments and sometimes you don't have to do anything at all! Some people are just super attractive to spirits and pick them up anywhere and they get followed home. This is why regular cleansing and protective practices such as head covering, carrying or wearing protections are so important.
Omg Lowe. What a story and for your friend to have to go through