I'm always amazed at the amount of idiocy some of you exhibit.
1) The hot dog and hallway commenters: For guys who have seen various vaginas (since this is an escort review board), you show a staggering lack of knowledge of female anatomy. Remember, a baby comes out of there, which is bigger than any cock, black or otherwise.
2) sleeping/fucking/dating others does not equate unhappiness in your relationship. There are other relationship models out there, practiced very successfully, and I, for one, am tired of hearing your monogamist bullshit.
3) OP: Maybe the cuckold porn idea is a good one, if you're both new to the kink. Another suggestion would be going to Oasis and seeing others play. Just be sure to discuss it, don't be afraid to voice misgivings, be honest in your reassurance, and remember, it's ok to back out if it's really uncomfortable.