These kinds of dates are forbidden in order to avoid temptation. What is acceptable for them in Shariah is for them to meet before their family members. However, some contemporary scholars prohibit the (frequent) family meeting and only permit her to be in the meeting for once, twice or thrice only.

Sheikh Abdullah bin Jibrin says: 

The fiancée who is pre-engaged woman is a stranger, and talking to her is like talking to a stranger so it must be done in an acceptable manner and within the limits, and only when needed, such as agreeing upon certain things for after the marriage and we must take into account the following:

1. It should be with the consent of her guardian and he has no objection to her marriage

2. The conversation should not provoke (sexual) urges and not lead to temptation/sin

3. There is no other way to tell her what he wants such as through his sister, or her brothers or a message

4. It should not go beyond the limit