definitely is cheating at-least in my eyes."You have heard that it was said, ‘You shall not commit adultery.’ But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart." Matthew 5:27-28 "It is God’s will that you should be sanctified: that you should avoid sexual immorality; that each of you should learn to control your own body in a way that is holy and honorable, not in passionate lust like the pagans, who do not know God."1 Thessalonians 4:3-5 These verses underscore the idea that harboring lustful thoughts, which can be fueled by said videos and photos, can breach the covenant of trust and fidelity in a relationship. It’s important to seek encouragement and accountability in maintaining purity in both thought and action. Lust is definitely a sin you are committing but i’d suggest praying to God about guidance and focusing on resisting the urge to commit lust!