Arranged marriage

I have talked to multiple guys during the AM process who have mentioned they have a gf or I found pictures on social media. Idk why guys are like this?? Anyway one said aisa hi hota hai he will break up with her and we’ll get married. I’m not going to say yes but if I did agree how can he just forget about her ? All their memories? What’s the point in getting attached to a girl if u know u won’t marry her… if they r doing so much for her, travelling together, talking night n day..buying gifts n all how can they move on ?