How to survive an unhappy marriage?

One enters into marriage with dreams of hoping to start a new journey with their partner that is filled with love and happiness. For a happy and successful marriage, both partners need to be equally invested to work towards it. With the marriage beginning to feel suffocating leaving you both unhappy is certainly not why someone enters into a marriage. I can imagine your pain and agony.

It would help for you and your spouse to go for marital therapy. What it would do is provide you both a safe space to be heard patiently without any judgement, address the issues causing suffocation and unhappiness in your marriage and explore ways to cater to the solutions to those issues.

However, for any measure to work, both partners need to be willing to invest and commit to the process towards the same goal and be on the same page about it. One sided efforts rarely last long and are not effective.
For the therapy to also work for you, you both need to practice the leanings of the therapy into your daily routine life outside of the therapy space.

To begin with, work on the foundations of your marriage.
Communicate with each other on a daily basis about the things that matter to you both. Make these conversations meaningful and deep, a time to establish an emotional connection with each other. Get to know each other's idea and expectations of this marriage. Choose your words carefully. It matters not only what you say but how you say it. Make use of a more responsible language than an accusatory language. Instead of playing the blame game, focus rather on the solution and how to achieve it together.Remember, it's not about winning against each other but being on the same team.
Address the conflicts in your marriage. What is causing them? What would both of you like out of it? How ca you achieve it? What must you both do to achieve it? Never take your troubles to bed.
Make efforts in the marriage to keep the love alive. Go on dates, surprise each other once in a while, whisper sweet nothings into each other's ear.

However, if nothing works, consider separation. Its better to part than to live together in misery.