The meaning of a blue heart emoji ? sent by a guy can vary depending on the context and the nature of your relationship. In general, the blue heart emoji can represent trust, loyalty, and stability, and may indicate that the guy values these qualities in your relationship. It can also convey a sense of calmness, peace, or serenity.
If the guy sends you other affectionate or romantic messages and emojis, the blue heart emoji may be a way of expressing his feelings for you. However, if your relationship with the guy is strictly platonic or professional, the blue heart emoji may simply be a friendly gesture or a way of showing support or appreciation.
It's important to remember that emojis are just one aspect of communication, and their meaning can vary based on the context and the relationship between the people using them. It's best to consider the entire conversation and the person's behavior towards you to understand their intentions better.