Are you falling into a relationship?
Some people fall into a relationship without even realizing it and can be taken by surprise.
You have camaraderie with someone else and develop a platonic relationship. You start hanging out together.
They become the go-to person.
In other words, if your friend suddenly couldn’t make it to a social event and you need someone else to replace them at short notice, guess who you are asking?
You start having lunches together. It’s just friendship. Oh so it seems.