What is why does he leave me on read and reply later?

When someone leaves you on "read" and replies later, it can be attributed to various reasons. Here are a few common possibilities:

1. Busy Schedule: The person might be occupied with work, studies, or other commitments and didn't have the time to craft a thoughtful response immediately.

2. Need for Time: They might need time to think about their response, especially if the message requires consideration or involves planning.

3. Emotional Space: Sometimes, people need a moment to process their emotions or thoughts before responding. They might not want to react impulsively.

4. Prioritization: They might prioritize other tasks or conversations before getting back to you. It doesn't necessarily mean your conversation isn't important to them.

5. Overwhelm: They may be feeling overwhelmed by messages and obligations, causing delays in response times as they manage everything.

6. Forgetfulness: It’s possible they intended to respond but got distracted and forgot to come back to the message.

7. Technology Issues: Occasionally, messages might be marked as read unintentionally due to app glitches or notifications being checked inadvertently.

It's important to have open and honest communication if this is something that bothers you. Discussing how you feel can sometimes provide clarity and improve understanding between you and the other person.