If Jonas were to continue in the community living among the others, I do think it would be difficult for Jonas to have a spouse.  Through The Giver, Jonas has learned to feel love.  This is not something you can come back from.  Any spouse that Jonas had would be purely for the purpose of raising a child.  The person would not love Jonas, and would not be able to even understand the emotion of love.  When Jonas asks his parents if they love him, he gets a lesson in language precision.  He wants to love his parents, and he wants to know that they love him.  That can never happen in his community.

 If Jonas had a spouse, he could not have a loving relationship with that person.  Jonas has feelings, and this person would have none.  Jonas also has sexual feelings, Stirrings, that the spouse would be suppressing with pills.  The relationship would likely be a very painful one for Jonas.

The main reason Jonas cannot have a spouse is that he cannot raise children.  By raising children, he would be perpetuating all of the aspects of the community that he has come to disagree with and despise.  He would not be able to love his children, he could not share memories with them, and he would have to have no meaningful contact with them once they aged into adulthood.  Since the others have no feelings, this is no problem for them.  It would be for Jonas.

I think that for Jonas as he is - with his characteristics and personality - it would have been impossible for him to marry and stay within the community. We see how he handles the "truth" of his society when he discovers the true meaning of "release" and how this gives him the impetus to act and leave, taking Gabe with him. Before this, however, we already see him withdrawing from his former friends, because he wants them to share what he is able to see and some of the good aspects about life. Marriage in such a community would have been impossible to Jonas, unless he managed to shut off a major part of his life and "play the role" that was expected by him.

It’s not the secrets that he would have to keep so much as the emotions he could not share. In “regular” marriages this is not an issue. Imagine, however, on a daily basis the unrelenting pain of emotion and memory Jonas would have to bare. To experience this in a partnership and not be able to share would have been tormenting.

Jonas cannot share all of the memories he is being given with a spouse. This means that he would be living with another, but living in a form of mental isolation. Imagine for a moment being married to someone who spoke another language, one you could never hope to learn yourself. What kind of marriage would that be? Jonas can now see things that no one else in the community can see and feel things that no one else in the community can feel. It would be difficult for him and a wife to live together in that situation.

One of the reasons that Jonas would like the Giver to accompany him on his escape is because Jonas knows this is one person who has felt and seen as he has.  If the Giver goes with him, Jonas will not feel so alone.  Similarly. while his motive in taking Gabriel with him is to keep Gabriel from being released, Jonas has already transmitted memories to Gabriel, making Gabriel another human being who will understand Jonas. 

I don't agree that it would have been difficult for Jonas to have a spouse if he had become the Receiver.

As Receiver, he would first of all have had to have all the books.  But his spouse and children would not have been allowed to see them.

Second, he would not have been allowed to say anything about his work.  As we see from Jonas's own family, family discussions about how the day went are pretty much mandatory in their society.

This would have made it harder to have a spouse, but still not that hard.  After all, Jonas's father keeps secrets from his family and nothing bad seems to come of it.  Jonas would have more secrets to keep, but you would think that his spouse would be so conditioned to obeying the rules that she would just accept that he couldn't talk about his job.