Hello Jessie,
Your example :
他紧张自己的利益可以理解,但是这可以通过商量解决。
I think this Chinese sentence has a little problem or mistake. “紧张” is seldom used as a verb in Chinese.
As you know, “紧张” is an adjective, and maybe you cannot find a reasonable word about "紧张" to function as a verb.
Because most of Chinese people don’t say “紧张自己的利益” in the daily life. They used to say “担心自己的利益”. Here “担心” means worry about ...
The word “紧张” used as a verb here, so perhaps you can change it into “担心” if you want. I think 担心 is better to use here.
I hope these answers can be helpful for you to understand the phrase. If you have any Chinese problems, just let me know.
^_^ Anna