Live by Example?

One of my friends has a really crappy marriage.  I feel certain her husband has cheated on her in the past.  She once found "proof" of inappropriate IM conversations, but he insisted that nothing happened outside of instant messaging and that it was "no big deal".  She turned a blind eye and decided it was acceptable as long as he didn't physically stray. 
Or I guess unless he was blatant about his affairs?  I dunno.  Seemed wonky to me.
I see them grow further and further apart each year.  I see them making the same mistakes that my husband did with complacency and apathy.  A prime example?  I called her husband more than six months before her 40th birthday.  "This is a big birthday. It's VERY important to her.  She's going to say it's not, but it is.  I need to know you know it's important so you don't drop the ball on this one."  I know it was none of my business, but I could see where it was headed.
He dropped the ball.  Of course.  And her response was to shrug it off and say, "I didn't expect much.  That way I wouldn't be disappointed."
Who wants to live like that!?  I don't mean she should have had high-in-the-sky hopes and then been pissy because he didn't follow through, but wow.  To just tolerate being treated that way...?  Oh.  And for the record?  She was extremely depressed and disappointed for weeks before and is still in a foul mood.  She just keeps saying, "Whatever... it's fine.  It's what I expected," but it's clearly not FINE.
I want to reach out to her/them.  I want to say, "Fix it or GTFO..." which is what I'd tell someone here on DS.  I want to offer her some of the knowledge, skills, and tools I've picked up over the last two years.  But.  I can't.  I don't want to be THAT person.  You know... the one selling Mary Kay or Jesus.  "OMG I'm just SO excited about this thing that's brought so much joy/peace/love/wonder/prosperity to my life!!!"
Because... as we all know... someone force feeding us their miracle cure (even if it has been a miracle to them) never works.  It's a huge put off.  If she asked, I'd have no problem sharing as much as she wanted to hear, but I don't think it's appropriate to butt in and "sell" her on having a better marriage.
So I guess in the meantime I have to just sit by and wait for her marriage to crash and burn and for her to eventually have her heart broken.  (Or for her to break his?  Guess it could go either way.)  That just seems so soul crushing, though.
Someone recently said I should just live by example.  Not like I'm any better than my friend by ANY means, just that I realized some things sooner than she has and by living in and enjoying the "new" marriage I have, maybe at some point she'll think to herself, "I want THAT..."  She deserves better, that's for sure.