I wish you would wait for me for three years.After that I will surely...
用I wish you would比I hope you can感觉软一些,请求的感觉重一些.
wait for someone,for一定要有.
for three years,时间前的这个for也一定要有.
I promise I will ...after that.盟誓的感觉重一些.After that I will surely...感觉是我当然会这样做的.
after then是时间三年以后.after that是你等了我三年这个事件以后.
所以具体怎么写,要看你想要给对方什么感觉,还有你这个...是什么.