How does Yunior see Lola as different from other girls? How does he feel about her? What do we learn about Yunior’s personality as a result?

Yunior has a rather ambivalent relationship with Lola. While he thoroughly adores her, he somehow finds it impossible to remain faithful to her. It is unknown whether this is a product of his cultural background or personal inclinations. Yunior, however, is an intriguing character and also the principal narrator of the novel.
For his part, Yunior is fascinated with sex; he sees women primarily as a means of fulfilling his physical urges. In spite of this, he has a special place in his heart for Lola, Oscar's sister. He sees Lola as a "tough Jersey dominicana." Lola is a long-distance runner who drives her own car. She is tough as nails, independent, and unconventional. Unlike the other Dominican girls, Lola is not fixated on outward appearances. However, she tends to revel in extremes. Yunior mentions with awe that Lola even shaved her head "Sinead-style," remaining oblivious to the radiating disapproval from the larger Dominican community.
In Yunior's mind, it is Lola's loyalty and dependability that sets her apart from other girls. When Yunior gets beaten up one fateful night, it is Lola who nurses him back to health.

She was the one who took care of my sorry ass. Cooked, cleaned, picked up my classwork, got me my medicine, even made sure that I showered. . . . Even though I had a girlfriend, it was Lola who spent those nights with me.

Certainly, Lola is not what Yunior would call his "physical type." She is almost six feet tall, small-chested, and dark-skinned. Yunior describes Lola as "one of those overachiever chicks who run all the organizations in college and wear suits to meetings." However, Yunior adores her; it is Lola's tenacious loyalty and dependability that inspires his worship of her. To Yunior, Lola is an enigmatic mixture of "ferocity and vulnerability." He admits that, unlike other girls, Lola totally confounds him. He does not fully understand her, yet she seems to comprehend him to his innermost soul.
As for Yunior, his personality is revealed in the way he describes his feelings about Lola. While he admires Lola and craves a girl with such decided principles, he is unwilling to meet her at her level. Yunior's description of Lola is almost entirely focused on the physical. To Yunior, physical intimacy is of primary importance. His shallow view of women and his decidedly superficial nature are certainly character defects; they prompt Lola to reject him in the end.