“It’s not really possible to have sex without feelings – it’s how humans are wired, asdfadsf ”

It's not really possible to have sex without feelings - it's how humans are wired, although some people try to fool themselves. What's important is to be kind to others. If you're not interested, say so instead of avoiding calls. If you're interested but the other person isn't, be gracious about it. Try to be wiser next time about giving yourself to another.