"Why Love Is Not Enough" is a common sense kind of book in the nicest sense of the word "common." If people could follow his advice, Sol Gordon would make an important decision comfortingly simple.

His premise is this: Love and sexual attraction not withstanding, some marriages are doomed from the words "I do," because the issues surrounding the union have not been thought through. Just understand the risks, Gordon advises, and decide which risks are worth taking.

If you are single or have children of a marrying age - and if you agree with the author that love is not enough - you might want to buy this book. It's inexpensive, short and easy to read.

"I'm not talking about anything fancy," says Gordon of his efforts to encourage the love-blind to make a rational decision. "If you think you've found the right person, the best advice is always to think again."

He writes, "My definition of a successful relationship is one in which, after the passage of a considerable period of time, the partners can still look up and say to each other, "I like you."

In the first chapter he asks you whether you are ready for a mature relationship. (Hint: If you want to get married as soon as possible, Gordon will not only offer no suggestions, he'll question your maturity. He says he doesn't deal with the desperate, though he does offer suggestions for dealing with your own desperation.)

In later chapters he talks about signs of mature love. "In marriage, the issue is not how compatible you are . . . the real issue is, how are you going to deal with the inevitable incompatibilities that are part of any marriage?"

He offers lists of questions for those in love to ask each other, including: - Should we save as much of our income as we can or try to live well on what we make now?

- How will we allocate household tasks?

- With whose parents do we anticipate spending most of our `in-law' time, such as holidays and family gatherings?

Finally, Gordon gives tips on who not to marry. For example: "Don't marry an addict . . . or someone who is `just like' a parent you feel you have a bad relationship with."

Gordon's common sense fails him in only one section of the book. He suggests the possibility of marrying someone you know is a homosexual.

He doesn't advocate it, he merely says many Ann Landers readers wrote in to say it works well for them. And then he suggests an AIDS test first.

Given how cautiously he approaches other differences in lifestyle - he warns of the danger in marrying someone who likes to live in a more modest home than you do, for example - his position on this fundamental and important difference seems glib and irresponsible.

Gordon's best advice is just to think about marriage before you do it and keep on thinking after you are married. He reminds us, "Love is not an ending point. It's a starting point."