In English, it is very common to end a sentence with a dangling preposition, such as "The man you are going out with." In French, prepositions can never be left dangling at the end of a clause. They must always come immediately before the relative pronoun.
Preposition + qui
When you want to link a relative clause to a person using a preposition, use the structure preposition + qui (meaning with whom, to whom, for whom, etc.).
For example, if you are talking about a partner you get along with (avec), you must phrase it as the partner with whom you get along:
| He is the partner you are going to get along well with. | C'est le partenaire avec qui tu vas bien t'entendre. |
| The man you are going out with is very attractive. | L'homme avec qui tu sors est très attirant. |
This rule applies identically to verbs that take the preposition à (to). Instead of the woman you are talking to, she becomes the woman to whom you are talking:
| The woman you are talking to has a beautiful personality. | La femme à qui tu parles a une belle personnalité. |
Using Other Prepositions
You can use this exact same pattern with almost any preposition when describing people, such as pour (for), chez (at the home of), or sans (without).
| She is looking for a romantic partner for whom humor is a criterion. | Elle cherche un partenaire romantique pour qui l'humour est un critère. |
| The boy at whose house we are eating is attractive. | Le garçon chez qui nous mangeons est attirant. |
| She is the woman he cannot live without. | C'est la femme sans qui il ne peut pas vivre. |
