The neuroscience of why attraction changes in long-term marriage, the Coolidge Effect, and how Islam's model of mawaddah and rahmah provides the solution.
In the first 12–18 months of a relationship, the brain is flooded with phenylethylamine (PEA), dopamine, and norepinephrine. These create the racing heart, intrusive thoughts about the partner, and the feeling that sex with this person is unlike anything before. This state is real. It is also temporary by design.
The brain is not broken when this fades. It is completing a biological programme. The question is what the couple builds in the space that opens up after.
Stage 1 — Lust: Testosterone and oestrogen drive initial desire. Stage 2 — Attraction: Dopamine, norepinephrine, and serotonin create the obsessive early love state. Stage 3 — Attachment: Oxytocin and vasopressin build long-term bonding. Couples who navigate from Stage 2 to Stage 3 consciously are the happiest.
The brain is a prediction machine. Once it has modelled a stimulus accurately, it reduces its dopamine response to that stimulus. This is called hedonic adaptation. It applies to everything — food, music, money, and partners. It is not a character flaw. It is how attention is allocated efficiently.
The Coolidge Effect (named from a famous psychology anecdote) describes how novel sexual partners trigger far stronger dopamine responses than familiar ones in most mammals. In humans, this biological pull toward novelty exists — but is not deterministic. Meaning, purpose, emotional depth, and spiritual commitment can override it.
The Quran does not promise that marriage will always feel like new. It promises something better: mawaddah (deep loving affection) and rahmah (merciful compassion). These are Stage 3 emotions — post-dopamine, post-lust. They are more durable, more healing, and more deeply satisfying over a lifetime.
"And among His signs is that He created for you from yourselves mates that you may find tranquillity in them; and He placed between you affection and mercy." — Quran 30:21
Fluctuating desire is normal. Sustained loss of desire for months may indicate:
All of these have solutions. The Sunnah emphasises health as a trust (amanah) — seeking help for sexual health issues is not shameful; it is responsible.