[Always *]

You're only 14, so the change of that happening are super slim, especially if the only basis is that your mom doesn't approve of him. And to be perfectly honest, I don't know if I blame her if he's encouraging you to do things like runaway or leave your family when you're way too young to do so. Even if she doesn't know about this particular plan, he might have said or done something that was a red flag. Alternatively, you might have told her something about him that triggered a red flag.

If you just leave home without telling your mom, she can report you missing / as a runaway and that can be bad. It doesn't matter if you're living with his family or elsewhere, the cops can still make you go home unless you can prove that you're being legitimately abused (physical, emotional/mental or neglect). In fact, your boyfriends family might get into trouble if you move in there without your moms permission, depending on the circumstances and laws where you live.

What you need to do is try talking to you mom first and ask her to give you and your boyfriend another chance. Tell her why your boyfriend is special to you, share some good qualities and then establish rules (e.g. you'll respect curfew, she has to know where you are when you're with him and you have to check in with her or answer your phone if she wants to check in etc.). That said, if she has very real and valid reasons to not want you in that relationship, you might need to just respect that.

Another thing to try is maybe you can invite your boyfriend over so your mom can meet him and get know him. Alternatively, maybe your family and his can have dinner together.

I can't emphasize enough that running away or otherwise leaving your family home just because your mom doesn't like your boyfriend is not a option. If other stuff is going (e.g. abuse) then you need to report it to family services and they'll help you. Another option is to research emancipation laws in your state.

I hope this helps.