There is a passage in Genesis where Isaac, thinking no one is looking, takes an opportunity to make some moves on Rebecca, his wife. I'm not a Hebrew scholar (nor am I the son of one) so I can't tell you what this passage looks like in the original language, but the English translations are fun. The KJV tells us that Isaac was "sporting with his wife". The NIV and NASB use the word "caressing". The ESV tells us he was laughing with her. J.N. Darby can't settle on sporting, laughing or caressing so he goes with "dallying" (Next time you are alone with your honey, ask her if she minds if you dally with her a bit).
Whatever the Hebrew word was intended to convey here is probably not as important as the fact that Isaac was doing something with Rebecca that sent a clear message to Abimelech that they were more than siblings (or really sick, but apparently that thought never entered the king's mind. Good for him!).
Issac married Rebecca when he was forty (25:20) and they had their first children - twins - when he was sixty (vs. 26). Later in chapter twenty-five Esau sells his birthright to Jacob after coming in from hunting, half starved. We aren't told how old they were but the impression is given they are grown men. I find it hard to believe Esau would have the authority to give away his birthright if they were just boys so let's make an assumption that they were around eighteen (although I think it likely they were older).
So it would appear Issac and Rebecca had been married for about thirty-eight or more years. Never mind that Rebecca was still a looker at this time. The important thing to note is Issac still took time out of his day to "sport" with his wife. There are a lot of reasons people stayed together in ancient times. It would be a bit romantic to assume it was only for love or God they stayed together. For the women security would have probably been high on the list of reasons. But this is precisely my point. Issac didn't have to pay much attention to Rebecca. She probably would have continued to cook his meals and have his children. But he didn't see it that way. He still enjoyed being with her and he let her know it.
Many husbands today take their wives and their relationships for gratned. Many women stay with their husbands for less than romantic reasons, even when he never gives her good reason to do so. I remember stopping by a garage-sale with my wife and an elderly man and woman waited on us. They were clearly husband and wife. So, wanting to be friendly, I introduced myself to the lady and asked, is this your husband. She said, "Who? This a** hole? Yeah, this idiot is my husband". It actually got less pleasant the longer we stayed. We made our purchase and ran away. We both swore (not that kind of swearing) to not let our relationship get like that. I think we have both secretly continued to pray, "God, please don't let us get like that!"
However, not getting like "that" takes work. Getting like "that" is easy but avoiding the tragedy so many find themselves in today involves the man getting off of his (what she said) and doing something about it lest he become a (what she said). One of the things I determined to do a long time ago is continue to sport with my wife. Now, that is easy to say when you are first married. But as time goes on it can take some effort. Not because she isn't pretty or lovable, but because we are men and we get this stupid idea (O.K., we have more than one stupid idea, but I'm focusing on only one for now) in our head that we are super attractive and that every woman on the planet would want us so this one we are married to should count herself lucky to have a hunk like us. Like I said, it is stupid. We aren't that attractive, we are just plain lucky and the sooner we realize that without divine intervention we would still single, the better.
Anyway, my point is that lady we are married to deserves to be treated like the hero she is (for marrying us in the first place and for putting up with us in the second place). Sport with her. Flirt with her. Laugh with her. When you walk into a public place grab her hand and smile big so people think that the lady you are with must be famous or something. Tell her she is pretty. When you are out in public, catch her eye and make that face that let's her know you are currently fantasizing about her. Sometimes I even write flirtations notes in church and pass them to her (nothing too steamy, it is church after all). And don't forget to let your kids see what you are up to once in a while. They'll squeal in protest, but with a little professional counseling they will get over it. They need to see how a real man romances the woman of his dreams, even after twenty-plus years of marriage.
The fact is, if we want our marriages to last then, as men, we need to make it happen. Will it always be easy? No. Will it be worth it? That is entirely up to you. As for me, I'm headed downstairs to superstitiously sport with my wife while the kids aren't looking.