Many of us struggle to live up to the ideals we see on TV, in advertising and on social media.
That's why for many people, whether they are in a relationship or not, days which are supposed to celebrate love and togetherness can only highlight how different, alone, or low we feel.
So we're using Valentine's day as an opportunity to share information and stories which might help if you're feeling this way on this day, or any day.
"Seeing other people promote their happiness on social media makes things feel even worse."
If you're feeling lonely today, think about why, take steps to build up your social connections (take it slow if you need to) and be careful when comparing yourself to others.
Self-esteem is how we value and perceive ourselves. It's based on our opinions and beliefs about ourselves, which can sometimes feel really difficult to change.
If you have low self-esteem you may feel like you dislike yourself, like you're worthless or no one likes you.
Days like Valentine's day can be difficult because there are a lot of portrayals of unrealistic and idealised relationships to measure yourself up to, and therefore a lot of ways you can feel you or your relationships are not good enough.
"I criticise myself in a way I wouldn't dream of doing to others."
If you are feeling any of these things today, or any day, some things that can help are being kind to yourself, looking after yourself and setting yourself a challenge.
Even if you're in a loving relationship, you can feel left out on Valentine's day.
Although going through difficult times together often makes our relationships stronger, they can also cause arguments or stress, and can make us feel like we are not living up to the 'perfect' image we see all around us.
If you feel this way, it might help to read George, Clare and Kate's blogs about how they manage mental health in their relationships.
George blogs about learning to support his girlfriend with her depression, and how he looks after himself too.
Clare and her husband both have mental health problems. She shares the ways they have learned to cope.
Kate blogs about how her relationship was affected when she became her husband's carer.
There is support out there for you are struggling.