The REAL question that he should ask is - does he LOVE his girlfriend truly, & so too she in return, AND NOT based his decision on material goods in the journey of life. The times spent TOGETHERr, thru ups & downs, & ability to overcome such would have to count for something, far more than mistakes made......
Disagreements & quarrels are only common in relationships, as life is no bed of roses daily, often due to money, time spent, etc & even as mundane as who washes the dishes.... Such only causes vulnerabilities, due to misunderstanding that each's need are not met, & sadly, when one is vulnerable, one's sense of comfort becomes a target by devious others.
Fortunately, not all would succumb to such temptations, & probably once or twice in their lifetime unless one is a sexual addict. All it takes for couples on the journey of life together is to give each other some space to cool off, then slowly pick up, discuss openly over issues, in order to proceed.
No Human is perfect & ALL are flawed, Each make mistakes in life - male or female, none spared, in order to learn, to correct & progress, thus EACH mortal deserves 2nd chances & more in life.
Trust lost is not easy to be regained back, but as long as there exists true love, it can be rebuilt again, to look beyond flaws & build a life's journey with a companion than to be alone, & such is priceless, worth far more than a mere BTO flat...
The power of true love will compel a mortal to greater heights than he/she can possibly imagine, or burn one to cinders if poorly managed & by advisements from inconsequential others whom does not live one's life.
Love pushes one to provide not just for oneself but for another & others beloved, & generations to come. When successful, what is a BTO flat compared to landed properties or overseas landholdings as well as prestige one can own?