I've had an embarrassingly long non-romantic obsession with someone, though it didn't involve a bf. I think I'm nearly over it now. This is what helped me:

• Looking at them objectively. A lot of what I thought was amazing about them were things I had exaggerated or assumed in my own head. I realized I don't actually like this person and they are pretty dumb. Why was I spending so much time thinking about them?

• Realizing they are a compulsive liar. This is why everything always seemed perfect for them. Everyone lies to a degree but some do it much more than others. Unless you can verify it elsewhere, assume everything has an element of deception.

• Building up my own life. It's very hard to be envious of X when I have X in my own backyard. I tried some of thing things I was envious of and realized I didn't actually want that thing! I just liked the idea. I also explored more of my own wishes unrelated to them. Gaining skills and qualifications helped me build self worth too.

• Removing the negative elements of my life. Doing this meant I was less likely to look for a fantasy escape to obsess over.

• Realizing that we didn't have the same start in life. They had a privileged upbringing. I had an abusive one. That doesn't mean they are better. It's interesting to see them struggle with things now that I learned to take in my stride from a young age.

• Stop checking and delete everything. It's normal to take a few attempts to be able to stop but each attempt will become easier and easier. At first just a day was torture but now I can months easily. Keeping busy with various personal projects helps a lot.