If someone's boyfriend said, "You have really let yourself go," it could be hurtful and damaging to the person's self-esteem. This comment suggests that the person has changed in a negative way, particularly in terms of their appearance or personal care, and it may imply that the boyfriend is dissatisfied with the relationship.
It's essential to remember that everyone's appearance changes over time due to various factors like age, stress, lifestyle changes, or health issues. Such comments can be insensitive and should be approached with care and empathy. Open communication and understanding between partners are crucial in addressing any concerns in a relationship.
If someone were to receive such a comment, it's essential to talk openly with their partner about how the statement made them feel and to address any underlying issues in the relationship. Constructive conversations can lead to better understanding and growth together.