<human>: My question is, what is the right decision for my sister(25) to do? Her boyfriend(26) has admitted to my father that he has no intentions of marriage until his "career" is stable, and he believes 26 is far too young to be engaged or married.

My sister expected an engagement ring for Christmas, but was devastated when she received some sort of "promise" ring. Of course my entire family was upset with this as well. 

It's pretty evident he has no intention of making a big commitment, and it feels like he's just staying with my sister for the convenience of it (cheaper living, sex, having a girlfriend). 

So r/Relationships, what do you think is the right thing for my sister to do?

Can you summarize the given text in a few sentences?
<bot>: Sister's boyfriend has made it clear he does not want the relationship to move further, what is the right thing for my sister to do?