am 5 year older than my boyfriend

Hey Guys,

My Name is Brenda, Please help me, l don’t know what to do. l am in a relationship with a guy who is a 4 years younger than me(discovered it late),he´s so sweet and all a lady would need in a man. Both of us work and we spend all weekends together.

Mostly we spend time out taking walks and he is also a good cook. Almost everything he does is so perfect and he wants to marry me. How do l tell him the truth that I’m  4  year older than him. Please I really Need your Advice .