我想你了 vs 我想你 1. 我想你了 I've missed you(when you were away). Or I begin to miss you now. "了" is a particle, which doesn't have specific meaning, but indicates completion. It could means either "I have DONE sth 了" or "Now I begin to DO sth 了". Say for example: If you meet your boyfriend, who left you for a long period, you can say "我想你了". means, I've ever missed you so much since you left me alone. Second, when you are talking to him right now, you can also use it to tell him your current feeling that is "我想你了", now I begin to miss you....... blah blah ^_^ -------------------------------------------- 2. 我想你 I miss you. It is present tense, simply means you think of him now.

如果是很久没见的朋友，可以说“我想死你了！”（I missed you so much.） “我想你。”（I miss you.） “我想你了。”（I am/was missing you.）

我想你了：有点过去式的意思，i have missed u 我想你：正在进行，i missing u.

“我好想你啊”更符合口语表达习惯，或者“想死你了” ”我想你了“和“我想你”一般是在还没有见面的时候，打电话，e-mail，或者视频聊天的时候比较常用

both are true