Willy misses the point and confuses "being loved" with being "well-liked" as it is evidenced in the fact that he takes almost for granted the love of his wife, Linda, and seems more eager to please and satisfy someone who shows him only shallow emotions when he enters the affair with "The Woman."
Linda gives Willy every possible validation he would need. She calls him "handsome," "smart," and she continuously showers him with complements and kind comments that would assure any normal man that he is loved.
Still, Willy grew up without real love. His father and, later on, his brother left him at an early age having to fend for himself in all matters of support and personal worth. Willy may very well have never known what it feels to feel loved, and so he embarked in a never-ending quest to be "liked." After all, to be "liked" often carries with it a lot of instant gratification, which Willy savors.
In his affair with "The Woman," Willy constantly asks her why she picked him, why she likes him, and other things that have nothing to do with true, emotional connection. As such, he also lacked this connection with just about everyone, including his own adult children.
The consequences of this lack of distinction are crass. Because of his ridiculous need for validation, Willy nearly destroys his marriage. While the marriage was saved, his relationship with Biff became permanently damaged when the latter found out about the affair. Willy also breaks relationships with coworkers, going as far as (supposedly) slapping someone when he heard the person call him a "Walrus."
I’m fat. I’m very—foolish to look at, Linda. [...] a salesman I know, [...] I hear him say something about—walrus. And I—I cracked him right across the face. I won’t take that. I simply will not take that. But they do laugh at me. I know that.
Willy is aware, fully aware, that he is NOT well-liked. Perhaps, he has never been well-liked, judging from the poor way that the treats his friends and neighbors. Therefore, this is one of the consequences of his desire to be well-liked: he fails. He tries too hard, and he loses each and every time. If he knew and validated love, and those who love him, he would not have to be in this endless cat-and-mouse chase for validation that has led him nowhere.