I Can Make You Love Me

Laura Black, a young and ambitious intern from Virginia, accepts a job at Kensitron Electronics International (KEI) in Silicon Valley, California. During a tour of her new workplace with future co-worker Chris, Laura meets long-time KEI employee Richard Farley, who immediately becomes infatuated with Laura's beauty. Richard invites her to a local tractor pull, but she politely refuses. Looking for a home, she later visits an apartment in Sunnyvale, and is accepted as a new roommate by the current tenant.
On her first day at the office, Richard is waiting at her new work station with fresh-baked blueberry bread to show his affections. In the days that follow, Laura enrolls in a local aerobics class, where Richard watches her intently. When the class dismisses, Richard meets Laura in the parking lot and asks her out to a concert and dinner afterwards; but again, she politely turns him down. Becoming frustrated, Richard then tells Laura that they can't have a relationship if she keeps turning him down. Laura is quick to correct Richard, sternly informing him that their relationship is strictly business.
Richard continues to make advances on Laura, convinced that he and Laura are in a romantic relationship. At a KEI softball game, Laura once again denies that their relationship extends beyond the workplace. During the game, Laura's new friend and co-worker Glenda Moritz takes note of Richard's infatuation with her, though Laura says she can handle him. Richard also becomes offended when he notices Laura and Glenda looking his way and laughing, thinking they are making fun of him.
Richard continues his hopeless pursuit of Laura. Through an excuse of wanting to present a staff birthday celebration for Laura, he is permitted by a coworker to see her personal dossier, from which he learns of her birthday and address, later showing up at her apartment with a gift. When her roommate tells her she should inform KEI management of the apparent stalking, Laura insists that she can handle Richard, saying that if she did otherwise, she would be his defeated victim.
Richard later slashes Laura's tires at her home. Laura calls the police about the incident, and suspects Richard as the culprit. Richard later confronts Laura on her suspicions, warning her that she'll be sorry if she sends any cops after him. Laura finally approaches KEI management to file a formal complaint; but management brushes it off, thinking that Richard only liked her because of her smile. However, management does instruct Richard to leave her alone at work, which he skirts by enrolling in the same non-work aerobics class as Laura. Richard later photographs Laura from the yard in front of her house, and uses the photos to doctor a picture of himself and Laura together. With the harassment progressing, Laura and her roommate relocate to a new apartment, which is gated for added security.
Richard later breaks into Laura's office during after-hours and discovers her new address, as well as her family records. Richard then threatens to go after Laura's sisters if Laura does not learn to accept that she "is meant for him." While visiting her family for Christmas in Virginia, a gift arrives: the above-mentioned doctored photograph of the two of them together, which Richard labels the photograph of them "on their summer vacation." Laura confesses the situation to her family, who insist that they help her get out of this before it boils over. Laura insists that she loves her job and will not let Richard intimidate her. Laura then files a second complaint at KEI upon her return, again with little effect.
On another day at work, an enraged Richard confronts Laura in the ladies' restroom, smashing the bathroom mirror and threatening her for not accepting his advances. Laura reports the incident to KEI management, and when Richard declares that he will kill anyone who attempts to interfere with his "private relationships," he is immediately fired for this threat.
The harassment continues on an irregular basis. Laura begins dating Sam Waters, who fears for Laura's safety. To protect her, Sam teaches her how to use a gun for self-defense. When Richard breaks into her garage and leaves a note on her windshield, Laura confronts him and he casually brushes it off with yet another advance. At work, Laura receives a major promotion that cancels when she is unable to obtain proper security clearance. Thinking the cancellation is because of Richard's harassment, Chris convinces Laura to serve papers on Richard for a restraining order, which turns out to be the final course of action that leads directly to the shooting rampage at KEI.
Enraged by the restraining order, Richard purchases numerous guns and over 2000 rounds of ammunition. At work, Laura is looking forward to her upcoming court appearance for the restraining order to become permanent. On that same day, Richard arrives at the KEI offices in an RV, bringing numerous shotguns, revolvers and explosives. He blasts his way through the lobby, firing at random employees. Richard blasts his way into the secure offices, shooting several more employees and killing Glenda. Richard bursts into Laura's office, shooting her in the left shoulder and leaving her for dead, though she is only unconscious.
SWAT units arrive and evacuate most of the building, though Richard remains holed up with dozens of hostages. While hostage negotiator Lt. Grijalva speaks with Richard; Laura, although weakened due to loss of blood, makes her way through the ransacked offices. Richard remains stubborn, and attempts to convince Lt. Grijalva that Laura is the guilty party for refusing dates with him, and insists that she was the one messing with him. Laura finally manages to escape the building and is rushed to a hospital for surgery on her shoulder, all the while blaming herself for the unfolding horror.
Richard continues his rampage, at one point executing one of his surviving victims, unknowingly shoots Chris through a wall, but also permitting Nancy to leave the building unharmed. Exhausted and thinking that he will die, Richard demands food while he considers surrendering. Hours later, the police produce the food but informs Richard that they do not have the proper means of getting the food to him. Overcome with exhaustion and dehydration, Richard agrees to surrender to the police. Seemingly unconcerned by the carnage he has caused, Richard asks Grijalva if he thinks Laura will remember all this.

Question: Why Richard become frustrated ?
Answer: Because Laura keeps turning him down , making him sad