Re: How do you move on
OP doesn’t mention who this other person was. A friend, colleague, etc. Maybe they saw them on a daily basis. Maybe it was someone who they spent prolonged periods of time with.
Sometimes it has to do with the memories you have just made in your head with that person. Some people go on and fantasize a relationship with someone and plan a future together without that person even knowing. It’s pretty crazy but it happens and its not something you plan to do but you just start perfecting the situation in your head and living a false reality. Then when it doesn’t work out you’re all heart broken when in reality the other person may not feel the same way or was planning on taking the relationship in that direction.
Contrastingly, even if someone isn’t a huge part of your life it doesn’t mean you cannot develop feelings for them. You may notice just one small good aspect about them and it may really intrigue you or allow you to become really invested in them. Again, very unhealthy, because you don’t know about other aspects of their personality that might turn you off. You just start focusing on their one good quality and become totally invested.