Dear Asha,
Why cannot you marry the one you love and get settled for an arranged marriage with him. All marriages are arranged by God and you cannot escape it even if you want to.
Here you are asking me if you go for arranged marriage, then you are afraid your ex-lover will come and haunt you. If not you are prepared for the arranged marriage. This means that your love towards your present lover is only ephemeral and you are prepared to marry someone else if he will not create any problem after marriage.
Am I right? This shows your sincerity in marriage and your love to him is not genuine. You are not prepared to live with him in thick and thin, come what may happen. There is no need of astrology to answer such questions.
Best of luck.