Break in relationship

My bf and I have been together for nearly 2 years. However we are currently on “a break” in our relationship which he initiated. His reason was that he wants to focus on career.

Its been 3 months that we dont talk to together. Should I send a text message to him for his birthday? today is his birthday. If i send the message what tone should it be? sweet like when we were together or just normal like friends?