Tristian was a 17-year-old student at a Texas high school when he says he was pursued by 29-year-old teacher Tanya Ramirez. Ramirez, on the other hand, claims it was the other way around.

“I actually had a friend that had her in class, and he came up to me one day and he told me that she thought I was cute, and that she wanted me to get her number,” Tristian tells Dr. Phil on Monday’s episode. “When I got to her classroom, we were talking, and then I gave her my phone and she put her number in. And the next day, we started texting.”

WATCH: Teacher Who Slept With High School Student: 'I Didn't Think It Was Legally Wrong'

Ramirez and Tristian say the texting, which they say turned flirtatious, continued for three-and-a-half weeks. Then, on the night of May 30, 2014, Tristian went to Ramirez’s house at 3 am, at which point they say they headed straight to the bedroom for, what Ramirez says was consensual sex.

“Did it ever occur to you to say, ‘I’m a teacher and you’re a student and it would be inappropriate for me to give you my number?” Dr. Phil asks Ramirez.

“No, because it wasn’t out of the realm of normalcy for teachers or coaches to have students’ numbers,” she replies.

“But you were neither teaching or coaching him,” Dr. Phil points out.

“Which makes it even more appropriate,” Ramirez says.

WATCH: Teacher and Student Recall Night They Had A Sexual Encounter

Ramirez pleaded guilty to an improper relationship between teacher and student. So why is the 31-year-old now suing Tristian and his mother? This episode of Dr. Phil airs Monday. Watch more here.