Thats sketchy. I feel like if he actually liked you that he wouldn't "forget about you." But also some people do the three day rule before texting back. Maybe he was joking when he said that but that is so rude. If I were you I would be offended and just move on
1. i doubt he lost interest 2. maybe hess trying to get you to text him more? 3. maybe he's trying to lower your value if he's insecure about his own 4. he's lost interest but i seriously doubt it 5. he's busy but i seriously doubt that would keep him from responding for three days
I said that to someone once and as a joke and thought it was hilarious but then realised after I sended it, it sounded horrible haha. If he's being serious though that's pretty crappy. You can do better than someone who 'forgets about you'!
I feel like he was just busy doing something else and when he realized he hadn't texted you for 3 days he wanted wanted to let you know that he was still thinking about you. I don't think he would have texted you if he didn't want to text you again.