In my situation mentioned above - it was more related to my inability to share my relationship with my mom. Plus, the age-difference was a "tough sell". She was 14, I was 17 at the start of it all. As time went by, 15/18, 16/19, it was more "acceptable" but you can only hide a girlfriend for so-long... There is more to it - but by the time she started to get sick of my long-distance relationship, she kind of got involved with thinking that her Sr. year in high school was something she wanted to focus on, got a new boyfriend and then we drifted apart. I still miss her. She actually moved to the city where I live now - but we've never spoken since '86. By chance - I saw her mother in a hotel pool in her hometown this last summer when I was up there visiting the area. That was freaky.

You may ask "why did you hide her from your mom?" - that was because my mom was my primary source of support, I was an only child, I was adopted and felt that at any time, she could cut-off my support of college funds and all that. That's how I lived my life - "try to make my mom think I'm doing everything she wants me to..." (but I was nowhere even close at times)