There's likely a psychological reason / association with "taking notice" to older men. --It certainly was for me.
While this may or not be true for all guys, I discovered later in life that I personally had been drawn to older men in particular because I desired acceptance and a "bonding" which I never got during my youth. I dunno.
Somehow? I just didn't seem to "fit in" nor get drawn into the friendship and fellowship circles of other men....whether my own age, or-- those who were older.
When my hormones kicked in during adolescence, my feelings for mixing and mingling with other guys (then) became "sexualized" (btw, a bonafide psychological term) and I became rather confused as to determining whether I was straight or gay. But my sexuality itself! --well, it never was
the culprit (i.e. the REAL root cause) of my inner feelings!
"What" I was noticing in the men I was oggling was a combination of admiration of their masculine bodies (like I wished I could have and/or be) PLUS the longing to just feel good about myself and be included ("bonded") with another guy. Often, I wanted to be like these men, emulate them or find ways to be more like them.
As the original poster said, it wasn't necessarily desiring a "boyfriend" type arrangement at all that I was seeking. I merely wanted to feel better (and more accepting) of myself as a man.
My youth, even the young adulthood phase of life....proved to be, very VERY confusing. Even tormenting for me mentally and emotionally.
The LPSG community truly assures me that I wasn't by myself!
--Too bad I couldn't know this back then!