As much as i wish to know and talk more about relationships, i really don't know much, maybe because am slightly an introvert but the little i know is that there is no beautiful garden without a committed gardener. The reason why your spouse is beginning to look less attractive to you is because you're allowing the weeds outgrow her roses or rather allowing unwanted plants germinate around him. Pluck them off and see if he/she won't match up to the other men and women you're admiring.
Since am a guy, i'll speak mostly to men who don't see a big deal in spending much on their ladies coz not all men believe that spending doesn't make it seem like you are weak in a relationship (Weak in the sense that even if she dumps you, you're still good to go man, life doesn't end there) infact that makes you a real man, don't be quiet when she's carrying her hair undone for weeks. It should bother you if she's been wearing those same torn shoes for months, when she visits you in those shoes, bro how do you feel escorting her to the bus? Stop by the store if she's not smelling nice, the Nivea roll-on and body spray package is not that expensive hoping you can afford it, and encourage her to be spraying it with the fear of God so that it will last (Winks).
Invest in her diligence and honesty
Invest in her principles by making her feel she has a purpose
Invest in her by actually teaching her to invest and save for future purposes (That's if you both think you have a future)
Invest in her way of life (Well, if it was me, i'd teach her to walk in the way of God)
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Invest in her Skills and help her in developing it for the better
Invest in her by making her see you as an help mate also
Relationships is not always all about saying that deceptive sentence - I Love You, It should also reflect in the sacrifice we must be ready to embark on with our spouse or partner.
Don't just be deceiving each other, Invest in your Spouse