Example:
Because he just wanted a one-night-stand, he told the girl he had a girlfriend, to make sure the girl [...]
Meaning that the guy told the girl he had a girlfriend so that the girl understood that he just wanted to play. So that she wouldn't expect a long-term relationship.
Is there an idiom for that?
Other idiomatic ways to express the idea that he wanted her to understand he was not interested in a long-term relationship:
...so she wouldn't expect a serious relationship.
...so she would understand he was just fooling around.
...so she wouldn't get the wrong idea.
...so she'd understand that nothing would come of it.
...so she'd realize this was a one-night stand.
what @tim romano said, plus
...wasn't looking for commitment
What @Tim and @Jeff said, plus:
so she wouldn't expect anything serious.
