Men who follow Instagram girls are thirsty losers desperate to drool over ass/tits for sexual gratification. They have no self-control and most of them tend to be porn sick and/or loyal as their opportunities.
Whether it’s cheating or not, it’s certainly pathetic and disrespectful. There is no “perspective” here besides the fact if he respects you and value your relationship stop drooling over other women and focus on your relationship.