It's a character flaw. If you can't be honest enough to stay faithful in a serious relationship, not including marriage, you can't be trusted period. I know what I'm talking about here.
I agree. All we truly have is our honor and our word. If I was in a committed relationship and found out that my S.O. was unfaithful, my trust would be just as destroyed as if I were married.
FWIW, I would wonder about a guy who was celibate for 10 years. I would think in that time he would have found what he was looking for. But, if I did decide to get involved, I would easily call for some sort of comment either way by 6 months. You might not know if a given person was someone you could marry, but you would know for sure it this person wasn't right. And I would be very upfront with him that if we anre't in a committed relationship leading to marriage, that I would date others if I decided to.
Which is why Honesty and not Fidelity would be at the top of my requirements list for marriage, or a serious relationship of any kind. Without trust, there is no relationship, and without honesty there is no trust.
My top five list for marriage would be:
1. Honesty.
2. Love
3. Respect
4. Compatibility
5. Attraction
Would you displace one of those with fidelity?