Why Bob always seemed to seek out the for dates was a mystery to all his friends; it seemed obvious to them that the reason was not, as his sister suggested, that he was looking for someone like his first girlfriend, who was rather loquacious.

Reticent

Explanation:

Reticent is defined as the person who is not comfortable enough for expression and extracting out his/her feeling or thoughts openly.They keep their feeling reserved and have mostly introvert characteristics.

According to the question,Bob is searching for reticent type of date This might be confusing for his friends as they have heard that Bob wants a talkative and open natured girlfriend.

i honestly speaking this is too long