If you are both in love, compatible in all important ways, and best friends, 4 years need not be an issue. Talking in depth about the specific reasons that you are concerned with a counselor, one-on-one can be helpful. There are 7 primary areas of compatibility that are good to address. You can learn about these in the book: Intelligent Love: Choosing a Lifemate Wisely. You can learn more about this book here:

Hi, Sure, People marry partners who are older than them all the time. As long as she's who you want, and she feels the same, it should work fine.

My partner of almost 11 years is 10 years younger than I am. I was 38 when we met, and he 28. I thought we were the same age; he has an old soul and I'm forever young. Our attraction was, yes physical, but moreso a comfort and trust between us that felt so right. I call him: My perfect man for me.

I don't know how old you are, but I think sometimes the biggest barriers with age come from teens into twenties just because one is in adulthood and the other is still in high school mode. Even still, if you're asking, you may not be ready for marriage (said lovingly); that, or one of you sees current issues bringing up the question. Think about what those might be and I believe you'll have your answer. : )