He wants to look at women in the street with the intention of proposing marriage

It is not permissible to look at women in the street, because Allah has commanded the believers to lower their gaze. Allah says (interpretation of the meaning): 

“Tell the believing men to lower their gaze (from looking at forbidden things), and protect their private parts (from illegal sexual acts). That is purer for them. Verily, Allah is All‑Aware of what they do” [al-Noor 24:30]

If a person opens this door to himself, that is a dangerous matter. At first the Shaytaan makes the idea of proposing marriage attractive to him, until this becomes a regular habit, then he looks at women with no intention of proposing marriage, rather just for the purpose of looking at their beauty. 

The man who wants to get married should not look at the unveiled women in the street, especially in that kaafir country where most of the people are kaafirs or immoral. Rather he should ask virtuous and knowledgeable people about virtuous and righteous women, and approach the matter in the proper manner. 

With regard to looking at women in the street, this is looking at their external beauty only, not their inward beauty which is more important than outward beauty. What is the point if a man marrying the most beautiful of women if she is lacking in good attitude and religious commitment? 

You should check yourself and review the qualities that you want in the woman you choose to marry, the most important of which is that she should be religiously committed and have a good attitude. The Prophet (peace and blessings of Allah be upon him) said: “A woman may be married for four things: her wealth, her lineage, her beauty, or her religious commitment. Choose the one who is religiously-committed, may your hands be rubbed with dust (i.e., may you prosper).” (Narrated by al-Bukhari, 5090; Muslim, 1466) 

The purpose of marriage is not merely to satisfy one’s desires and enjoy intimacy, so that the man need care about nothing more than beauty; rather marriage is more sublime than that. So you should study the true qualities of your potential life-partner, those qualities that will make your life happy and calm, not a temporary happiness that will disappear as desire fades, leaving nothing but trouble and sadness after that. And Allah knows best. 

It is not permissible for you to show your friend the women to whom you propose marriage, and it is not permissible for him to look at her. A man should have protective jealousy (gheerah) concerning his wife and his honour. The Sahaabah were impressed by the strong gheerah of Sa’d ibn ‘Ubaadah (may Allah be pleased with him), and the Prophet (peace and blessings of Allah be upon him) said: “Are you amazed by the gheerah of Sa’d? I have more gheerah than him, and Allah has more gheerah than me.” Narrated by al-Bukhari, 6846; Muslim, 1499.