guys that want one thing

I've been talking to this guy for months, it was going great, we talked about meeting and seeing each other and then he sent me a pic and kept asking for some I never gave him any but when I asked if he is serious about us or just wants to walk away he said I feel really horny for you and sent me another picture when i asked him is that all he thinks about with me I got a yes. Why does this keep happening my ex moved on so easily and 3 years down the line and I still find dicks! I need help!!