At this point you might be wondering, like the disciples did in Matthew 19:10, "If this is the case, maybe it's better not to marry."
That is an important decision. Depending on the severity of the red flag, a friend may be able to address them while remaining in the relationship. And not every red flag mentioned here is of equal importance. For example, a friend's alcoholism or another friend's tendency to avoid conflict don't necessarily hold the same weight. It's not about looking for the perfect mate; if it were, we would be disqualified ourselves.
Raising a concern in the relationship needs to occur with honesty, humility, and kindness. You might voice qualities about your friend that you do appreciate before sharing your red flag. For example, "I find your kindness and compassion to be great qualities in your life, and I greatly appreciate them. Recently I've been struggling with the amount of time we spend together. I know it's important that we have the opportunity to share time, but I'm feeling suffocated in some ways." The focus is your experience and the behavior itself, not the trait. "You're too dependent," may or may not be accurate, but it's going to be difficult to receive.
It may help to ask your friend to think or pray about it; maybe you're the first person who has ever had the courage to voice the concern and it may take some time for it to register. Your friend may disagree with you, but one's willingness to consider the concern will shed considerable light upon your subsequent decisions.
Remember that you're not there to fix your friend. Several years ago, a psychiatrist named Dr. Negri tried to do that and failed miserably. He "fixed" his younger patient of thirty years and subsequently married her. Their marriage ended in divorce. When asked why it didn't work out, he said that he had forgotten to do therapy on himself.
In some cases, you may be wise to take a step back in the relationship, at least waiting until a situation is addressed before moving forward. Keep in mind that a person can white knuckle a problem at least for a period of time; using sheer determination to change behaviors. That type of change is not likely to last, and may lead you back into deeper problems some time down the road. If a relationship needs to slow down or not move forward, you may need to identify the reason, discuss what steps each may take to address the concern, and agree upon the needed boundaries. Communicate clearly: Is the relationship exclusive at this point or not? Is there freedom to see other people? It will be important for you to know what changes will need to happen in order to move forward.