Be strongly obsessed with sb

Obsessed 这个词的意思是：(对…)着迷的;(受…)困扰的;(为…)心神不宁的。

If someone is obsessed with a person or thing, they keep thinking about them and find it difficult to think about anything else.

如果有人沉迷于一个人或一件事，他们会不断地思考，发现很难再去想其他的事情。

例句：
I stalked you because I am strongly obsessed with you

我跟踪你因为我太为你着迷了。

This changed my life as I become obsessed with the search for secret of life.

这改变了我的一生，因为我开始痴迷于研究生命的奥秘。

be fascinated by someone

这个词也可以表示为为某人上头，就是被某人迷住的意思。Fascinated 可以表示为入迷的；极感兴趣的。词典里面翻译为：having your attention fixated as though by a spell. 你的注意力像被咒语所吸引。

例句：

It's a subject that has always fascinated me.

这是一个永远使我着迷的话题。

We also offer our sincere love of interstellar hegemony-it is a world fascinated by people.

我们也衷心喜欢着星际争霸&它是一个让人着迷的世界。

on the spur of the momen
t

这个词有一时冲动;心血来潮的意思，spur 表示为激励;刺激;鼓舞，那一瞬间，被刺激，那么这个词就有上头的意思。

例句：

On the spur of the moment，he asked her to marry him.

一上头，他就向她求婚了。

go to one's head

这个词可能是最像 up head 的表达了，最好记。就是上头的意思，表示为使...冲昏头脑;使...飘飘然。例句：
This sad tale is by no means an imaginary example, it is a fitting illustration of the principle that it can be dangerous to allow fame to go to one s head.
这个悲惨的故事决不是一个虚构的例子。它是一个合适的例证来证实这个道理：假如答应让名誉占据一个人的头脑，那是很危险的。