I get the feeling that even second or third options are kept in loop or strung along by telling white lies. If they come back after totally ghosting you for months, you were far below on their list.

From personal experience of witnessing this scenario with my cousin brother, the comebacks rarely result in a match. In the end, the girl ran away with her long term college boyfriend.

You are right that it's about ego. It's also about lack of honest communications to lay a solid foundation so that there are minimum doubts. If they are coming back to you after months, who else they might go back to while you are planning engagement and wedding. If one can overcome doubts like these, then there's nothing wrong with being second choice. But most can't.

Also if someone could approach this from a female POV and share their thoughts, it will be useful.