Its all personal to me.
I am in a committed relationship with the man of my dreams. I am 22 and he is 21. My birthday is Jan 1984 and his is June 1984. So he is a couple months younger than I am. BUT we click like I never thought I would click with another human being. Our goals, our plans, our lives, our personalities; they're on the same level. We can argue like its the end of the world and discuss things for hours and then cuddle up and life is just absolutely perfect.
Before now I was in a few relationships with guys of all ages. When I was 13 I was with an 17 year old - we were together for 4 years. When I was 16 I was with a 22 year old - we were together for 2 years. When I was 20 I was with a 29 year old and we were together for a year.
I don't get along with a lot of guys my age because I don't drink or do drugs or party or care of bar/club scenes and I'm ready to settle down and have a family. MOST of the guys I know that are my age are still at the point where they are sweet talkers to the girls to get what they wanna get and then wanna get together with their buddies and oogle those 13-17 yr old girls who have jus discovered they can use their boobs to get wot they want.
Saying that though, guys older than me... seem to be at a place where they aren't sure if they want to have a family at all and would rather just let things happen as they happen if they happen and would rather set goals to get that new stereo or car than save to support a family. And guys much older than me... either already have the family thing or know they don't want it.
My sister is currently 15, will be 16 in July and she is dating a 20 year old. I don't agree with it for a few reasons. 1) he's a pig. 2) she's naive. 3) he's a pig. As much as I want to support my sister, he is one of those guys I mentioned before; a sweet talker who jus wants to have his fun with his buddies and oogle the young girls. I also know my sister very well and know she deserves better than him and his piggish attitude. I know he's going to hurt her; and I know Im gonna be there to comfort her when he does.
I think its inappropriate for young men to just look at younger girls. Younger girls are naive and they are insecure and they don't know themselves as well as they like to believe they do. Unless the guy KNOWS the girl and really has feelings for her I think its sneaky and wrong of young men to look at younger girls. Some girls act more mature and look more mature than they really are and if older guys (18+) are always setting their sights on those younger girls; I think those insecurities grow and can consume a girl.
But, its a personal matter. If you're gonna put your heart into a girl or a boy; you should make sure you know what you're getting yourself into. If you're a 20 year old boy and you wanna be with a 15 year old girl; ya just gotta accept that she's 15 and not 20. When she shows signs that she's 15, and not as mature as she may seem at times - you stepped into that and you can't blame her for being like that.
My sister and her boyfriend have been together for 2 years. He's 23 and she's 19.
My brother and his girlfriend have been together for 9 years. He's 24 and she's 22.
My dad and mom have been together for 30 years. He's 56 and she's 48.
My grandpa and grandpa have been together for 50 years. He's 72 and she's 64.
And they are all just as much in love as they were when they first got together.
Love happens at all ages and to anyone. Letting love happen is the hard part.
Age and maturity and love don't ALWAYS work together.
Everyone at every age experiences and shows signs of immaturity.
Everyone at every age can feel different types of feelings.
I don't think an age means a deeper level of relationship can be achieved.
I do think a deeper level of relationship means maturity can be achieved.
Its all personal to me 
PS:
Sorry for the novel 
___________________
You Will Always Get What You Have Always Got;
If You Always Do What You Have Always Done.