Is texting another woman cheating? UPDATE

Do you think it’s cheating if you’ve caught your SO texting another woman? I’ve caught my boyfriend doing this three times already. The last time was last year but it’s made me into an insecure person and has changed me(it’s what a lot of our fights are about)

I always forgive him because he is soooo nice and good to me and does anything for me. I just don’t understand how he did that three times. Do you consider this cheating?

UPDATE: sorry I had to update. These women knew nothing about him being in a relationship. They were under the impression he was single and looking. One even had a kid. Pictures etc were exchanged.