When my wife got knocked up (presumably by me) she stop cursing me realizing that her market value have drop significantly and she'll have a hard time finding alternative. I also start making more money realizing now that most of it won't fall to my enemy. At least my kid carry my gene.
Considering all the trouble a woman have to go through to pop one of those out, by evolutionary process, she'll be genetically hardwired to "love" the kid too.
Perhaps, competition is not the one and only ingredient for all healthy relationships.
Perhaps naturally irrevocable mutual interest will do the job to. I got to review my game theory book more.