Don't be fucking ridiculous. Of course it's not normal. Why are you even asking? Your "boyfriend" is 13 years older than you. He's got some fucking problems dating a girl your age. If your parents don't know about him, they need to. A 28 year old guy who's interested at a young girl like you is dangerous. Leave.
Your age 15 , in most states below the age of consent and he is age 28 a man whose old enough to know better. If you were age 16 that would be age of consent right now your not even the age of consent. So yes for now it's wrong and not normal.
Meh. Not normal, but nothing wrong with it. Little media-controlled wannabes whining here doesn't make it wrong. Someone that age is usually as developed as they will be four years later, at least physically, so unless you are some very naive kind of person, there is no problem with all that; unless of course if you are American (if so, I am sorry for you), then you may not legally have sexual intercourse.
This dude needs to be locked up
That age difference is staggering. Hopefully your boyfriend knows the legal age of consent in your jurisdiction and acts accordingly.
You're technically a minor, you're not even old enough to give sexual consent, drink, drive or be legally called an adult. That man should know better. You shouldn't be dating someone like that, it can be pretty concerning, like why would a guy who's nearly thirty want to date a teen? They're not always of sound mind.
if you're in the mid 20's , yes it will definitely be normal even if he will be 15 years older than you.. but kindly use and carry your brain sweety , he will take advantage of you and if you're not lucky enough you'll be in big trouble going to a court.