Is a girl obliged to agree to marry a suitor whom she psychologically rejects, despite his religiosity, good character, and comfortable financial situation, especially after performing Istikhara seven times and not feeling acceptance towards him, particularly with the insistence of her family, her feeling of guilt towards the suitor, and her fear of not finding a suitable alternative?

There is no requirement for Istikhara (guidance-seeking prayer) to see something [in a dream or vision]; rather, Istikhara is about proceeding with the matter, and if it is facilitated, then it is good. The suitor is a stranger to the fiancée, so extensive conversation with him should be avoided except to the extent of necessity. True love develops after companionship, and the required Islamic characteristics are din (religiousness) and khuluq (good character). If the suitor is religious and of good character, then affection will arise after marriage. It seems there is an improvement in your acceptance of the person, so calm yourself, dismiss negative thoughts, and give yourself an opportunity to think after seeking advice from those with sound judgment. The decision is yours, and no one has the right to impose anything on you. There is no sin upon you for rejecting him or breaking off the engagement, and sustenance is in the hands of Allah. Strive in supplication and seek Allah's help for matters to be eased.