Has he entered his third decade of life without a solitary long-term relationship? Or are things only so-so in bed -- because he clearly needs a little schooling? "Eek. Red flag!"

Okay, not so fast. Having a checklist of classic deal breakers may not be your best strategy for ultimately winding up with a winner. Dating coach Evan Marc Katz says the smart, successful 21st-century woman especially has the tendency to look for flaws early on and nix men quickly -- no one wants to waste their precious time, after all. But this habit may lead to you kicking a lot of decent guys to the curb.

1. His past is filled with a long trail of women.

"There's this temptation to move faster, but people reveal themselves slowly, over time," Katz explains, insisting that a dose of discernment can go a long way. "There's always nuance in every situation. We can talk about red flags and generalizations, because there's no other way to talk about people -- but we need to have the wisdom to realize that generalization isn't always reality."

Let's practice that sage wisdom. Here are a few red flags that may not be as bad as you think.

2. He's not one for foreplay.

If his figurative black book is as long as the dictionary, don't panic. According to Katz, many men want to reach a certain place of emotional and financial readiness before settling into that super-committed, long-term relationship. "He might have been having fun until he was ready to settle down and isn't necessarily a womanizing terror," Katz says. "It's not realistic to expect he wasn't going to date or have sex with anyone until he was ready to meet The One."

Katz says what matters are his intentions now. Figuring those out comes down to ascertaining his character. Does he have a history of cheating, or has he been faithful in past relationships? Does he treat people respectfully, or do you see signs of uncaring behavior or entitlement? If there are other big red flags, that's an issue. Trust your gut.

3. He's behind in his career.

Everybody knows that women need some extra attention before doing the deed... right? Even if it seems your guy is the only one who didn't get the memo, it doesn't have to be a dealbreaker, says couples counselor and psychologist Karla Ivankovich, PhD, an adjunct professor at the University of Illinois, Springfield. Since lots of men grew up with the quick encounters of hookup culture, they may need a little help fostering a deeper, closer intimate relationship.

4. He can't seem to say "I love you."

"Communicate," says Ivankovich. "If your partner is receptive to exploring your intimacy together, set parameters for how to go about this. Discuss the idea that talking about sexuality and preferences in an intimate way is very different from the physical act of having intercourse." But note that it's equally important. If he's not open to improvement so everyone's happy, it's best to move on.

So, you've got the corner office, and he's still trying to "make it" in an unconventional career path. If he seems to have all the makings of a supportive partner otherwise, don't be so quick to write this guy off. We're a generation that's raising the bar on happiness and that isn't keen on settling for a ho-hum career, which means it's taking some people longer to figure out who they want to be. "Ask yourself if he's got realistic dreams, or is he living in a fantasy? Does he have a plan, or is there no follow-through?" Katz says, noting these aren't questions you'll likely be able to answer after just one or two dates. "You have to see how someone reveals himself over time."

5. He won't bring you around his family.

If his inability to say those three little words has you reeling, calm down and chill out, says Ivankovich. There are many reasons a guy might not be able to say "I love you" besides the fact that he doesn't feel it, especially if he's generally an affectionate good guy otherwise.

"Before running for the hills, first see if you can address why this is an issue," Ivankovich explains. "Maybe he fell hard in a past relationship and his words were rejected. Maybe this was not modeled in the home he was raised in." If you can show him those words are safe with you, he may suddenly feel he can be vulnerable -- and won't be able to stop showing you the love. "Far too often, the younger generation is quick to dispose of things that don't work for them in the moment," says Ivankovich. "But the truth is, life and love are about commitment and sustainability."

He's got a big family gathering on Labor Day and isn't inviting you? What gives?

The Genius Trick for Perfect Scrambled Eggs
What's Your Sex Number?
The One Thing Hairstylists Wish You'd Stop Doing
The One Thing Dermatologists Wish You'd Stop Doing
Jennifer Aniston Shares Her Health and Beauty Secrets
4 Things Men Hide From Their Wives

Since mom and dad are generally still pretty involved in the lives of their adult children, Ivankovich says it's very possible he's taken an ex around his parents before -- and that she either didn't mesh with the clan or didn't get rave reviews. "While this has nothing to do with you, it can have everything to do with meeting the unrealistic expectations of parents in 2015," she explains. "For your partner, quite possibly, he may want to solidify your commitment to ensure you are not going to be harmed by critical family members." So if your relationship is still in early stages, let him get to that big introduction when he's ready. If you're committed and solid, and he's still trying to keep you hidden, then it's time to ask questions.

You can write anyone off for his history or flaws. But if you do, you may just write everyone off. The real deal-breaking red flags: "Liars, cheaters and emotional or physical abusers are never an option," Ivankovich says. Otherwise, take each man on a case by case basis and give him time to reveal his character to you, naturally.

Also on HuffPost: