I never had a boyfriend. :(
I couldn't say, as I've never had one.
That depends on the boyfriend and how much self esteem you have. A good boyfriend is fun, and accepting of you and your quirks, and compliments your strengths. They make you feel important.
A bad boyfriend will lie or cheat. Or they will put you down and tell you that you are lucky to have them. They try to control your life and tell it is because they know what is best for you. Don't ever fall for these type, It goes from bad to worse with them.
When you have the "right" boyfriend - meaning that you guys are compatible and have fun together - it can bring you a lot of joy.
The downside to having a boyfriend or a girlfriend is getting together with someone you don't get along with, or someone that abuses you, or someone that argues about every little thing and thinking you don't have a choice except to stay with that person.
Life is too short to waste time on someone you don't like or don't get along with just so you don't have to be alone.
I will never know. The thought is disagreeable to me.