Hi:
First off, I'm writing from "the other side"--I'm prolly old enough to be your mom and have gone through my share of heartbreaks (and they don't stop when one marries).
My first "True Love" and I were together for just over four years. We were planning on marrying five years to the day we met (the date would have been on a Saturday) but had we married I would have put a bullet in my head. Thank heavens that one's in the distant past (27 or so years ago--how time flies).
Since then my relationships (prior to meeting the guy who was fool enough to marry me) were usually a matter of months and rarely was I given any explanation of why it was suddenly over.
As far as "term limits", it could just be that those relationships were not meant to last "forever" (however you define it). If you can get analytical with yourself (divorce yourself from the hurt), go back through the relationships and see if you can a common thread in them that caused them to last about the same amount of time.
1. Did your "True Love" start to change in a way you weren't happy with (or vice versa)?
2. If you had an increasing number of fights towards the end (which I did with my first TL), what was/were the fight(s) about?
3. Did either of you develop a separate enough life from the other such that you preferred life alone to life with the other?
4. Did either of you have friends that the other one didn't like that may have gotten in the way?
5. Did either of you have some kind of behavior that derailed the relationship?
6. How was communication? Did you both talk heart-to-heart about things that were important to you, some possibly painful?
I didn't marry until I was 38 and had figured I never would. Didn't bother me at all--I got a great deal accomplished before I married and I wouldn't have changed anything for the world. My now-husband and I waited five years before we were married. I know I was terribly cautious because I was so scarred from my first "True Love" that I wasn't going to make the same mistake twice if I could help it. I needed to see him in as many different situations as I could before I could truly commit.
You don't say how old you are, I'm guess mid-20s? I just don't think your number has come up yet. What kind of support system do you have? I'd start taking advantage of it--your friends see sides of you that you don't realize exist and might be able to give you some suggestions, especially any female friends. They definitely see sides of you that your male friends don't.
I hope this helps. Please keep posting--PM me if you want.