I'm 25m in love with my best friend and my girlfriend
I'm very surprised to hear that you are in love with two people. Are your relationships with them going fine?
I'm doing fine but my relationships are not
It's normal to fall in love, but it is going to be hurtful to someone if you are in love with two people at the same time as a person may get jealous if they found out and you do not want to hurt them. If I were you, I will focus on the one that I really love and see a future with, so that you don't hurt the other person's feelings in the process.
I can't choose, I love both of them.
I understand that, and I feel for you, but it is only appropriate to have one relationship at a time so I still recommend you choose one of them. If it doesn't work out, then you should break up with them and see if the other person is interested with dating you. This way, you don't hurt any feelings and you are only dating one person at a time.