You can't judge a couple's relationship by how much they mention and/or communicate with each other on twitter! Not everyone feels the need to share their every wind-breakage, row, snog and shag on twitter!
Unfortunately, there seems to be this idea that a couple are only in love with each other and happy together if they broadcast it on the internet. If they don't, then they must be unhappy/on the verge of splitting up!
It's not just Twitter, though. It's also the fact they never seem to be together. I personally think one of a married couple going abroad without the other is a classic tell-tale sign that the end is nigh. Like I said, hope I'm wrong.