Meaning:

“积木型” means “building block-type,” and

“关系” means “relationship.” The term “building block relationship” was coined by Chinese netizens to describe a connection that is capricious and vulnerable, particularly between two lovers. When two individuals are in a “building block relationship,” things are either extremely sweet, and they are deeply in love with each other, or conflicts can cause the relationship to totally fall apart. This description also applies to friendships.

Example:

A: 你弟弟打算什么时候结婚？

Nǐ dìdi dǎsuàn shénme shíhòu jiéhūn？

When will your younger brother get married?

B: 不知道。我感觉他和女朋友之间是积木型关系。

Bù zhīdào。 Wǒ gǎnjué tā hé nǚpéngyou zhījiān shì jīmùxíng guānxì。

I’ve no idea. It seems to me that he has a very unstable relationship with his girlfriend.