There's rhythm in a friendship. You meet a person and the establishment of how you both are going to handle the relationship comes with time. It's a negotiation process, they say. What you like, what you don't like, stories, other relationships, work, family, hobbies, even diet play a role.
Time is the most difficult aspect. Sometimes you are free, but you want to spend time doing something on your own, and it's hard for some people to understand this preference.
The second most difficult aspect is when you decide to change a habbit, because it'll have an impact on the rhythm that was set. The other person may feel it has to do with a change in the affection.
I've just had this problem with a friend who I like very much. I have quit drinking and smoking, but she can't accept it. We meet and she insists on offering me both things,and she gets upset when I decline it. It's like I wasn't fun anymore. She also wants to include me in her often trips to the beach, although she knows I'm renovating my house now, and I won't take a time off until it's done.
It got weird. It's like we have nothing else to do together. I started feeling guilty and avoiding her contact. I don't believe I have to explain myself. I've already told her the new facts, but I'm not going to say why I took those decisions, because it'd sound like I'm wrong in some way.
I'm not sad, I just look at the situation and think how fragile relationships may be.