No, I have no idea to whom you are referring. The only thing I could possibly think of is Perrin, but he was regarding the customs as genuine obstacles to a quick wedding, and had no problem with the idea of getting married. Nynaeve DID make up a Two Rivers custom, but not to avoid marriage, she used the fake custom to invent a de jure relationship status that matched her perception of their de facto status. She told Lan that his giving her a ring back in tGH constituted a marriage proposal in the Two Rivers, as an excuse to insist upon their marrying as soon as possible. Two Rivers marriage customs had no bearing on any of Mat's relationships, and he never once brought up the difference in customs, though if he truly did not want to marry Tuon he could have plausibly used his ignorance of the Seanchan custom as an excuse. As far as Rand goes, he never once mentioned Two Rivers customs to Elayne or Min, though the differing perceptions of courtship he & Elayne both brought to their relationship left them both confused about where each stood with the other. For example, Egwene's suggestions to Elayne, though received with incredulity on her part, might have actually been the more prudent course of action. At that point in his life especially, Rand is sort of oblivious when it comes to women, and subtlety does not work on him (as Berelain had recently discovered). If Elayne HAD proceeded according to Two Rivers methods, Rand might have been hesitant about moving along that fast, but he would have been absolutely clear on where she stood. As it was, after Berelain had given him an impromptu lesson in how subtle and sophisticated women don't necessarily want a commitment before engaging in physical expressions of affection, and given his own self-esteem issues vis a vis Elayne, he had a hard time conceiving of her long-term or sincere interest in him. Meanwhile, thanks to her own inhibitions, she felt used and unappreciated, because he was not apparently reciprocating her feelings. So, this would not have been a case where Rand used Two Rivers customs to evade commitment, though it comes the closest. His incredulous reaction to their trilateral agreement to share him was not specific Two Rivers customs coming to play, but just his general condition of sanity. Not even the Aiel go in for foursomes. Finally, there is his marriage offer to Aviendha, but again, the customs he cited are not that extraordinary, and are perfectly believable to Western society in general, if a bit dated today. And this was not a case of using the customs to avoid marriage, but rather citing the customs as the source of his obligation to marry Aviendha after "taking advantage of her." And of course, Aviendha refused, because by her customs she could not in good conscience accept (it had nothing to do with whose place it was to propose - there is a reason why RJ had her face hidden when Rand proposed: so he/we would not be overtly shown how she wanted to accept - by Aviendha's code of honor, she had poached on Elayne's claim, which she had pledged to uphold, and so thus could not in good conscience take what she had promised to protect for Elayne. Plus in her eyes, his phrasing of the proposal no doubt seemed like a man touched in battle demanding to be made gai'shain to recover his honor.

So, no. I have no idea what Emond's Field customs were used to evade a relationship.