When’s the right time to have sex

Okay so I’m 19 and I’m in my first actual relationship. We’ve been dating for a couple of months, but still haven’t had sex. I’ve had sex before but it feels like every time I have sex with someone I genuinely like they leave. So the feeling of is he gonna leave after we have sex is holding me back from having sex with him. I’ve talked to him and he’s willing to wait a little longer until I’m fully ready but I don’t want him to lose interest in the meantime. Idk what to do here 🙃🙃

Currently looking for ideas on how to get over the feeling of him abandoning me and how to keep him satisfied still even if we aren’t having sex so he doesn’t lose interest.