my iphone thinks an android number is an iphone

Hi,

So my boyfriend recently got a new number. For some reason my phone thinks it is an apple phone and so sends it via imessage. I saw this question asked previously but no solution was given. Here is some more info:

1. He has never owned an apple product (before or currently)
2. I have a friend that can only text via imessage so I don’t want to turn the whole setting off.
3. I can still text him if i turn off wifi/data so it is forced to send as an sms, it is just very annoying to have to do that all the time.

Any ideas?? thanks!