"我对他没有兴趣。"

Translation: I have no interest in him.

[wowineedashit]

If you listen carefully, you can hear a heart shattering in the distance.

[g-c-]

I looked this up on Pleco since DL gave no explanation whatsoever.

In this context, 对 seems to be a preposition that means "with regard to; concerning."

I could be wrong, but that was the only definition that made sense.

[RemieSmith]

Thank you!

[RemieSmith]

I also found Google Translate says it can be translated to: Be opposite, so perhaps its meant in a sense like a, "I have no interest in being his other half" sort of thing. Really could use an official explanation

[kalexchu]

Not in this context, no. "Other half" is usually translated quite literally as "另一半".

[Gabrielle145359]

In this structure 对 is a preposition, which has the same function as the "in" in "to be interested in something" or "to have an interest in something."

[LightKnigh4]

Does it have a romantic meaning as in English?

[Gabrielle145359]

Usually.

[jim140738]

哭

[sJGMo]

No need for gan3 in this case?

[jamesjiao]

没有is followed by a noun and 不 is followed by a verb. So unless you change the sentence to use 不, then no.

[quadrin]

No grammatical explanation at all. Way to go.

[NasuSamaruk0]

他 is treated as the object, whereas 我 is treated as the subject. In the given sentence, 对 is treated as the "relationship" verb (which can be thought as "to treat" or "towards") between a subject and an object.

If the given sentence is

我对他没有兴趣。.

then the literal built blocks are

I "treat" him without interest.

or

I do not have interest in him.

More info is here.