You asked about how you could be more in control of what your happiness is dependent on. The answer is to determine the truth and to accept the truth. The truth seems to be that your best friend has a boyfriend and other people with whom she spends time. There’s nothing wrong with that as she is a normal person who wants to have relationships with various people.
It’s also common for females to spend time with their friends until they have a boyfriend. It’s often the case that females will ditch their friends as soon as they get a boyfriend. Males may do this as well but it seems more common among females. If the two were to break up, she would likely spend more time with you.
The same would likely be true for you. If you had a partner, you would likely be spending more time with your partner than you would with your best friend. This would be especially true if the relationship were new and you were attempting to develop that relationship. Because you only have so much time, you would have to divide up your time. It would likely be the case that your new partner would be taking up most of your free time. It would be understandable and you would probably expect your best friend to understand. You wouldn’t be doing it because you didn’t like your best friend. You would be doing it because you are attempting to develop a new relationship. That is normal and expected.
It is not something to be sad about because it is simply a fact of life. Your friend is in a relationship and relationships take time and a great deal of effort. As her best friend, she likely expects you to understand. It has nothing to do with you personally. It has to do with the fact that she’s attempting to develop a relationship, presumably in an effort to eventually marry and have her own family. From a human development perspective, this is the expected life course trajectory for the vast majority of people.
Perhaps you’re sad because you are taking it personally. You might think that she should be choosing you over her boyfriend but that’s not fair or realistic. As mentioned above, if you had a boyfriend living in the same town as your best friend, you would likely be doing the same thing. It wouldn’t be personal; it would simply be you trying to find your life partner which is something virtually everyone is attempting to do.
We can’t control situations but we can control our emotional reactions to them. Your friend spending time with her boyfriend is not personal. It has nothing to do with her relationship with you. She’s not acting irresponsibly or doing anything wrong or abnormal. It’s okay to feel sad but realize that she has the right to happiness. Hopefully, you can accept the truth of the situation, and stop taking it so personally. Perhaps then, you will no longer have an emotional reaction and instead be happy for her. In all likelihood, she would be happy for you if you were in a similar situation. If this continues to bother you, consult an in-person therapist. Good luck and please take care.
Dr. Kristina Randle