The relationship between John and Abigail is a bit complex. It's made clear to readers that John had an affair with Abigail months before the play begins.
I know how you clutched my back behind your house and sweated like a stallion whenever I come near! Or did I dream that? It’s she put me out, you cannot pretend it were you. I saw your face when she put me out, and you loved me then and you do now!
We are never told who initiated the relationship, but that doesn't change the fact that it was completely inappropriate from multiple angles. The Proctor family was Abigail's employer at the time. John is also a married man with kids. He should absolutely know that having sex with a teenager is inappropriate. Elizabeth Proctor discovered the infidelity and had Abigail dismissed. John has worked very hard to secure Elizabeth's forgiveness, and he makes it a point that he will never reach for Abigail again.
Abby, I may think of you softly from time to time. But I will cut off my hand before...
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