1. Blessing SMS: Send a short and friendly blessing SMS or private letter on social media to express the wishes for the other party's birthday, such as "Happy birthday to you! I hope you have a wonderful year. "

2. Cards or gifts: Their relationship is still friendly and respectful. Consider sending a birthday card or a small gift to express your blessing and concern. Choose some neutral gifts and avoid gifts that are too intimate or have special meanings.

3. Face-to-face greetings: The your relationship allows you to wish each other a happy birthday face to face. You can make an appointment, meet or express your blessing and concern through video call.