An oversimplified scenario goes like this: Your spouse strikes up an opposite-sex friendship with a person at work, spin or yoga class, the gym, or through your child's school or extra-curricular activities. For some reason, they feel compelled to exchange phone numbers. There's no real need for this, although your spouse tells you that they need to stay in touch because of work or to coordinate fitness class, the kids activities, etc.
Timing matters a lot, when you are trying to seduce a married woman with text messages. If you are aware of her routine and know she checks her phone in the night, text her during that time. The chances of getting a reply are also high if she has free time on her hand, and you may as well build up a conversation with her. If she is busy in the morning and you text her, she may dismiss it as annoying. So, time your texts and the replies to her text smartly, in order to make a lasting impact on her mind.
On the day of the date, you want to shoot her a text, preferably early in the day and long before you’re going to meet up. This ensures you that it’s still on and tells her that you’re still in. She’s most likely doing the same thing that you are: waiting for that text so that you both know for sure that you’re both still in and not going to flake. By doing this, you almost guarantee a no-flake scenario between the two of you.