Answer:The answer depends on the definition of "lust" that you use.
Technically, the word means, in both Greek and English, a very strong
desire. In both languages, it is most frequently used for a strong
desire for something that is not lawful. "But I say to you that everyone who looks at a woman with lustful intent has already committed adultery with her in his heart" (Matthew 5:28). Thus, as it is used in
Matthew 5:28, it would be wrong because it is talking about a strong
desire for sex with someone you to whom you are not married. Such
would not be the case between a husband and wife since the strong
desires are supposed to be there.