Sun in the second house of the composite chart is the best possible position for any business or professional relationship whose primary aim is to make money or to gather material possessions.
The second house is the house of things that are valued, either tangible or intangible. Sun in this house gives you a strong drive to seek whatever it is that you collectively value. The point is that you will go after whatever you want, and you are likely to succeed simply because you put so much energy into the effort.
In a personal relationship such as marriage, in which you own things together, those things will be very important to the security of the relationship.
One danger of this placement is that there may be a conflict of values between you. It will not be easy for the two of you to compromise on such issues, so it would be best to decide whether your values are compatible before you embark on any kind of joint venture.