1) Finances: when your income drops below that you'd envisaged for a comfortable life.
2) Friendships: buddies are important to expats since we're strangers in a strange land so when you fall out it affects you more.
3) Stimulus: having something to do is essential, especially if you're retired. Some are happy downing Chang everyday, shooting the breeze or sounding off on forums, others need a bit more to keep them going.
4) Business: constantly having to watch your back for snitches, competitors and other envious expats can be a drag if you run your own business here.
5) Relationship: arguing or drifting apart from your wife/girlfriend can cause serious problems, for many it was the reason they came here.
6) Politics: having to fight harder every year just to get the paperwork to stay here takes its toll, there are plenty of good alternatives to Thailand.
I've been through quite a few of these!
