I think that all signs indicate that the relationship is coming to an end.
First, Bart has stopped talking about the future, and has even said that the relationship will not last for all that far into the future. This indicates a change in his behavior, even though he may still act the same -- it is not the same. He is no longer thinking long-term. Actually, maybe he never really was thinking long-term, but he was just talking about the future because he thought that was what he was supposed to do. You say that Bart used to discuss the future, and my question is -- how did Sydney respond? Was she willing to discuss the future, or did she just blow it off, and maybe if she did, Bart got the impression that she wasn't interested in a future with him. Buying someone diamonds and gold says nothing about anything -- all it says is that he can afford to buy someone diamonds and gold. I don't think it means anything more than that, and does not mean that there will be a future to the relationship.
You say that Sydney is weak and stays with him, so it sounds like she's not really happy. At this point, it seems like the two of them are together more for convenience -- do they even really love each other -- are they even really in love? It doesn't sound like it -- it sounds like the relationship is wasting away, and any number of gifts won't stop that. Maybe Bart's projection of 10 years doesn't really mean 10 years -- maybe it means "I'll stick with you until I find someone better, but anyway this relationship isn't permanent."
Here's what I think -- I think that Sydney should, if she is interested in staying in the relationship, sit down with Bart and say something like, Dude, what in the hell is up with us? Where are we going and what are we doing? If they can't have that conversation, or if they don't want to have it, or if he sticks with his 10-year projection and she wants more than that, it's time to say goodbye and get the hell out, now. Either things need to get better or it needs to end -- there's no sense sticking it out as things slowly get worse and Bart and Sydney grow apart and come to resent each other.
But that's just what I'm thinking. Life is too short to stick around in relationships that aren't giving us what we want.
