1) Are other people and things a priority?
When the game, his boys/her girls, or anything else always seems to come first, then you are probably involved in a childish crush, not a real relationship. Real relationships put a priority on the relationship.
2) Can you openly and honestly talk about your relationship?
Honesty and communication are two huge parts of a real relationship and mature marriage. If there is concern which prevents you from having a real talk, or issues continue to come up when you do have real talks, it may be more childish than real.
3) Is he/she there for you when you most need it?
Flat tire, sick, hurt, need help with work/school, or just in the middle of a mess. Are they consistently the one who shows up in dire times? If so, you are in a real relationship. If not, it may be a childish crush, or he/she just may be more selfish than selfless. Either way its not good.
4) Do they keep commitments with you?
Late for dinner. Canceling your plans. Not calling when they said they would. Relationships, especially marriage, are built upon commitment. You cannot have a real relationship or a mature marriage if commitments are broken more than they are kept.
5) Do they sacrifice their comfort for you?
This could be giving up their jacket because you are cold, or allowing you to watch your show versus their show. When he/she is willing to be uncomfortable so you can be comfortable, then you can bet you are in a real relationship.
6) Are they respectful of your parents, your family, and your friends?
If someone has intentions of staying around they are going to do their best to have great relationships with those you love and care for most. But don’t be fooled. A childish crush can fake it until he/she makes it, but over time the real will come out.