You can decline tactfully in the following ways:

1. Express your concerns and concerns. You can tell your boyfriend about your concerns, such as that you don't want to take the risk of getting a credit card, or that you're worried that a credit card will cause unnecessary debt and stress.

2. Provide other solutions. You can suggest that your boyfriend find other ways to solve his money problems, such as seeking other loans or trying to save money.

3. Maintain your position. You can express your position firmly, such as that you don't want to get a credit card, or that you don't think now is the time to get one. At the same time, be gentle and respectful and don't let rejection turn into an argument or conflict.

4. Give positive suggestions. You can suggest that your boyfriend find other solutions. For example, you can suggest that he develop a financial plan or help him find other ways to deal with money problems.

In general, be gentle and respectful while standing your ground. By offering alternative solutions and giving positive advice, you can help your boyfriend understand your concerns while offering other ways to solve the problem.