My apologies in advance, I don't want to insult anyone but why we Bea has to be sad and feel lonely? What if she is really happy right now, as she is, without a known/serious relationship? And why a relationship that doesn't lead to marriage should be concidered as a waste of time? Again, my apologies because I might have misunderstood the tone of some dishers.
I think it's because Bea was with Dave for roughly 10 years, getting romantically involved soon after ending things with a convicted murderer. She was in her late teens when they met and started dating and, after being together for 5, 6, 7 years, people (public, press, her family and, from what we've heard, Beatrice herself) assumed they would get engaged. For a while, it was a quartet: Bea + Dave and Eugenie + Jack. On top of that, it appeared (to me) that Dave was using Beatrice for her royal connections (i.e.., bring her on those vacations and whatnot to hobnob with famous people who wanted to met royalty). Unfortunately, Dave dumped her soon before her 28th birthday, got together with someone else, got engaged AND is now expecting with that new girlfriend. That has got to hurt!
While I can't speak for the other Dishers, I think I feel bad for her because, based on interviews and accounts and whatnot, Beatrice is a lovely girl who deserves to be with a man who treats her with respect. So far, she hasn't found that man, is approaching 30, and now her younger sister is engaged! While I'm sure Beatrice is super happy for Eugenie I wouldn't be surprised if, deep down, it has got to sting a bit and she might even have a bit of a cry and, truth be told, I wouldn't blame her.