Can ex (or secret admire) become friends again?

Long have I seen this question, pooping up again from time to time... The real question is, can you become friend again with ur ex or secret admirer (or crush), friend? Well, most of the time... you can. But easier said than done, most ppl need time in doing so... some months, other years! A girl I once have a crush on rejected me, and I didn't want to see nor talk to her until like... 3 years later. Well, maybe I'm lucky (or not?)... but she got married, so I can feel 'better' when talking to her, not that awkward anymore. What can I say? Time will slowly heal a wound... but lucky I confronted her and expressed my feelings that time, else I will be 'stuck' like I am with 'her' until now... So take that final blow and heal later! lol...