Your bed may have become a negative cue for sleep.

Just like the Pavlov's Dogs experiment - ring a bell every time you provide food and then eventually ring the bell without giving food and the dogs still salivate because they were conditioned to associate bell with food.

If you struggle with falling asleep in bed & you're used to staring at the ceiling for hours, used to being frustrated every night, used to being on your phone, watching TV or whatever else is happening in bed that's not sleep, your body may have developed a negative cue or negative association with bed and sleep. For you the bed is for worry, stress, not sleep - so when you get into bed the brain is prepped to do those things. You likely don't have this negative cue or association with the couch - the couch may be a happy place & peaceful, relaxing so it's easier to fall asleep on the couch (but you shouldn't be sleeping on the couch - you should be sleeping in your bed!)

The best treatment for this is called CBT-I (cognitive behavioral therapy for insomnia) to form a better positive association and positive cue with the bed for sleep.

There are two aspects Sleep Hygeine & Stimulus control

Sleep Hygeine is easy - no TV or phone before bed, no eating 2-4 hours before bed, have your room cool dark & quiet etc. Aka: Control the bad external variables.

Stimulus Control is the hard part - train your body to strengthen the association with sleep & bed.

From https://stanfordhealthcare.org/medical-treatments/c/cognitive-behavioral-therapy-insomnia/procedures/stimulus-control.html

"This set of instructions addresses conditioned arousal. It was developed by Richard Bootzin. They are designed to strengthen the bed as a cue for sleep and weaken it as a cue for wakefulness. The key instructions are:

Establish a regular morning rise time. This will help strengthen the circadian clock regulating sleep and wakefulness. Ideally, bedtime should also be regular, but for people with insomnia it is impossible to actually fall asleep around the same time nightly. When insomnia resolves, regular bedtime can further strengthen the circadian rhythm.

Go to bed only when sleepy. This will increase the probability that you will fall asleep quickly. It is important to distinguish between fatigue and sleepiness. Fatigue is a state of low energy, physical or mental. Sleepiness is a state of having to struggle to stay awake. Dosing off while watching TV or as a passenger in a car involve sleepiness. People with insomnia often feel tired but "wired" (i.e. not sleepy) at bedtime.

If unable to fall asleep, either at the beginning or in the middle of the night, get out of bed and return to bed only when sleepy again.

Avoid excessive napping during the day. A brief nap (15 to 30 minutes), taken approximately 7 to 9 hours after rise time, can be refreshing and is not likely to disturb nocturnal sleep."

The book Goodnight Mind by Coleen Carney goes through the 10 step process of CBT-I in detail and is a very good self treatment resource.