She immediately regretted her decision.

He already regretted when I'd only said it.

Tom said he regretted what he'd done.

He regretted lying to her.

Tom and Mary said they regretted not following John's advice.

Tom did something he immediately regretted doing.

Tom regretted getting that tattoo, so he had it removed.

Tom and Mary said they regretted doing that.

Not a day passed by but he regretted what he had done.

He regretted having quit his job.