Newer relationship that already feels as if we're an old married couple?

I met a wonderful man about 3 and a half months ago. We get along great and he is incredibly thoughtful and sweet. The challange I'm facing is that we have met during a troublesome time in both our lives. We've been there for one another through it all so far, but it seems that we seldom have time to do anything fun together. We don't get to have any real quality time. It is a caring relationship, but there is not much affection between us either. We are getting through the hardships that we are facing, and I'm seeing a slight change in both of us, but we've both agreed that we've seen each other's best & worst, but skipped over that initial middle part! How can we get that part into our relationship, and continue to grow? After 3 months he is pretty certain he will marry me. I don't think I can say that based on 3 months with someone, but I could be wrong. I think that everything will smooth out soon, just wondering if I should just go with the flow. Thanks!!