DH and I have been together for nearly thirty years and I love him deeply and without reservation because:
He is utterly unselfish in everything he does.
He is kind, affectionate, thoughtful and warm; he tells me he loves me every day
He makes me laugh
He doesn't appear to notice all my hideous bits
He has always taken an equal role in all things domestic (well, he's done more than his share to be honest
)
He works so hard, but rarely complains
He is an amazing dad
He is spontaneous and always thinks about what would make me happy
He is not reluctant to apologise when we have squabbled
He is always clean, gorgeous-smelling and well-dressed
Of course, give and take is one of the most important elements - if someone does all of this for his/her partner and it is not reciprocated, then the relationship will probably falter.
Best of luck, CptCaveman. I hope to see you promoted in due course to Commodore Caveman, or Major Caveman - depending on which branch of the Armed Cave Forces you are attached to 