It's very exciting to believe a lifelong relationship is likely, and it's pretty common in the first 3 months or so. But those are rose-colored glasses that both of you were looking through. I wonder if there's an age difference between you and him. It would be useful to inquire into the extent of his depression history, since it's also possible that his overwhelmingly expressive passion might have been a bit manic. 5 months is a pretty good relationship lifespan for the first fundamental differences to emerge as much more of the whole personality comes into play, of both of you. How did you feel about him when his work worries and depressive symptoms were taking him over? We do live in a very unstable economy now, but I'd be concerned about his stability for keeping a business afloat.
You seem to be intent on a relationship that leads to marriage, because if this relationship grinds to a halt again, you will have wasted your time. (You could also approach him differently, as a good man whose physical and emotional intimacy could test and expand your own character and range of behavior, whether you make it to marriage or not.) Is this the first time you have felt so strongly that this could be the one? If it's not, then you have already learned about some personality traits that emerge midway into the first year and are so disappointing to you that you don't want to accept them in a life partner.
Public affection doesn't seem like a deal breaker for people considering marriage, since there are so many more essential elements in a relationship: Such as being able to admire your partner even 5-10-20-30 years later, being able to defuse an argument, caring for and supporting each other in sickness and in health. Can he manage his depression with medicine and/or psychotherapy? Can you see yourself giving him the support and respect he needs, even when he can't give you what you want because of his mental illness? [By the way, that takes a pretty devoted person who can stand by and care for their partner even when no amount of wind beneath his wings will lift him off the floor.] I've watched 35 to 55 year old unmarried men break up with a woman because of personality weaknesses like depressive--withdrawal--tendencies. But the same couple would most likely stay together if they were already married, while the partner whose expectations of the relationship have been dashed for the time being will adjust by developing greater satisfaction in other areas of life, like work, passionate projects, church and other rewarding associations.
If his depressive symptoms are sufficiently entrenched to be a significant threat over a lifetime, you'll need to face the questions I've raised above. Freud said the cure for depression was work. I would add that the biological function of depression is to kill off those members of the tribe that can't contribute to the welfare of others. So the cure is work that is so meaningful to the man and probably some part of the society that he will repeatedly overcome his depressive episodes by commitment to his passion for excellence in his chosen work. This sort of personality cycle is typical of a great many artists of all trades, but it's often not in good balance with caring for a spouse and family.