Good question—when is it gaslighting, and when is it bad communication? Here are his examples, with my opinion following. (A caveat: I don't know this person nor do I know any of his current or former partners.)
Example 1: "They tell blatant lies."
"I wasn't trying to keep my ex unsteady. I just wanted to get away with something or didn't want a long conversation."
Answer
Wanting to get away with something is a motivation of gaslighting. The question is: why did you want to get away with something? Because your partner wouldn't approve, or because, like you said, you just didn't want to get into it (presumably because your partner wouldn't approve)? You can gaslight someone without trying to keep someone unsteady. But it still can have that effect. A healthy relationship is one where you have healthy communication and don't try to "get away with something."
Other differences between gaslighting and poor communication—did you want to get away with something just because you could, or because you wanted to do an activity your partner wouldn't approve of? Was the lie one that would cause your partner to be upset and distracted, thus allowing you to get away with what you were doing? For example, did you fabricate a fight just to have a reason to get away? Gaslighters have an ulterior motive—and it usually involves gaining power and control.
Example 2: "They deny they ever said something, even though you have proof."
"Various reasons: I didn't want to have a long conversation; I wanted to get away with it. She would misunderstand what I had said."
Answer
"I wanted to get away with it" sticks out as a gaslighting motive. Doing something just to see if you can get away with it is a common tactic of gaslighters—it's a power and control move. It's also a form of self-preservation—you want to engage in a behavior your partner probably wouldn't approve of. But the way each of these three things were accomplished was by denying you said something you actually said. That's where the gaslighting comes in.
