Very young marriage

Ok so a friend of mine whom I havn’t seen in about 9 months now has texted me saying she and her boyfriend both want to get married. She is 19 but I’m not sure how old he is I guess 19 or 20) I met him a few times and is a nice guy. Turns out her boyfriend is all for it. However she says that she is really afraid that she is not good enough for him. Now he is definately one of the nicest guys I have met. As in top 5, no joke. She is afraid she is not good enough for him. Of course I ask what could be so bad?

She replies that mums have told their kids to stay away from her. Now I am thinking a few things here, just my personal thoughts

1. She is very much a girl you do NOT want to mess with, and is very strong (embarrasingly she beat me in an arm wrestle no sweat)
2. She is a NO-SIT girl. Basically someone tries to screw around with her or tries to rip her off then she will do something about it. She will not take sht from people. Like I know she smacked someone over because they called all her friends something which I will not put here and carried on like this for 10 mins or so and she got real pissed off and yelled at the guys to shut up (rudely though) and they keep going so she does her thing.
3. Moari blood in her which is known to get violent particularly when drunk. However she only gets violent if she really gets upset by something/someone and then it is serious.

I think the mothers decisions were made by a combination of these three with only having their own point of view.

Now what you have to realise here is that it is not he thinking that this is bad, she thinks its bad and that she may not be good enough for him.

However despite being 19 and maybe 20, they do seem to make a good couple.

I did tell her those people are not part of the marriage, the marriage is you and him. Why would you let some mothers rip ya out of a marriage? You love this guy isnt he more important than these mothers?

Just to be a pain, my phone stopped working properly (it does this) and now I can’t recieve texts. I also told her I rthink it may be lack of self confidence or it is self insecurity. What can I do or tell her? I do think they should be together seeing as they both want to get married.