I am sorry for the heart-breaking news you received from your boyfriend. It is never easy to hear that someone you like “likes” to look at other women in a sexual way.
Let me offer one comment to your statement and two answers to your questions:
Your boyfriend says he likes to look at porn. Does that mean he is admitting/confessing that his sinful nature is drawn to it (like hundreds of millions/billions of people)? Or does that he mean he likes it and plans to keep looking at it with no regard for you, for God, or for the clear passages of Scripture about porn (Eph. 5, 1 Cor. 6, Mt. 5, etc.)?
My answer to your questions is nearly entirely based on his attitude towards his sin.
Will he stop when you get married? I don’t know. We at CtC know conquering habitual porn use is not easy, but it is possible. With a constant reliance on God’s love for sexual sinners and a constant willingness to confess sexual sin to others (friends, pastors, counselors, significant others, etc.), there is incredible hope that porn will become part of his past.
But make no mistake–Getting married, having sex, etc. will not “cure” his problem. Sin is stubborn and porn will not go down without a fight. (That’s why I mentioned above that his desire to fight this sin is so crucial.)
What if he doesn’t stop? If he has no plans to stop, I would caution you against marrying him. A man who vows to love you but plans to despise you through his porn use knows nothing about Christian love and will break your heart with his digital harem.
If, however, he hates his sin, loves Jesus, and wants to love you with pure eyes and a sexuality that belongs only to your marriage, then the choice is up to you. You have idols, too, and he has to wrestle with the same question–Is he ready to love someone who will sin against him? Are you ready to walk with him on this long journey that leads to heaven, even if it means he battles porn for years, if not decades of your marriage?
I can’t tell you what to do (nor is that my place). I can, however, tell you that a man who loves God, hates sin, and wants to go to war against porn is a great man with a great Spirit within him. Those are the ones you might not want to let go of.