Every relationship is different, but there are a number of fundamental issues that a healthy relationship needs. Without them, you may not have a relationship worth having. But if they're present, you have someone who deserves your love. You have a right to expect all these things from your partner - if any of them are missing, your relationship may not be all you think it is …
Trust is one of the most important parts of a relationship. You need to be able to trust each other; it's what makes it difficult for a relationship to recover if one partner has cheated. If you can't trust him, you'll be living with uncertainty and doubts, and always wondering if he'll do the same things again …
You also have the right to be respected at all times. He should treat you with consideration, listen to your opinions, and never dismiss your feelings as unimportant. Your achievements and positive qualities should be valued. A guy who does down your accomplishments or laughs at your feelings isn't a guy who truly respects you.
Your boyfriend should also be completely committed to you. Unless it's a casual relationship for both of you, he shouldn't have one eye open for something better to come along. He should also dedicate enough time to you, and not prioritise going out with his friends.
A good partner will want you to grow and develop as a person, rather than always staying in the same place. He won't complain that you're trying to better yourself, or try to discourage you from achieving your dreams and goals. In fact, he should want you to grow and progress, and support you in achieving those goals.
You also have the right to be a part of any important decisions that he makes, such as taking a job in another city or going back to school. Anything that affects you means that your opinions should be taken into consideration. If he doesn't at least listen to your opinions, even if he ultimately decides to do what you'd rather he didn't, he's not considering your feelings at all.
As your partner, he should also be there for you whenever you need him. When you have problems at work, medical issues, or emotional upset, you should be able to count on his support. He should respect your feelings and not be distant when you really need his support.
Finally, it's so important that he accepts you for who you are and loves you for yourself, not who he'd like you to be. If he tries to change you physically or psychologically, he's not truly in love with you. It's one thing trying to encourage you to look your best, and another trying to make you into the way he wants you to look.
If any of these things are missing, you may realise that you've had nagging doubts for a while, but chosen to ignore them. A good partner is worth having - but it's better to be single than be in a relationship with someone who doesn't love, respect and cherish you …