Crying over a boyfriend isn't just the over-dramatic actions of an angst-ridden teen or young adult girl. The reasons why a girl would cry over her beau are plentiful. From acting aloof to cheating and lying, a boyfriend -- both the good and the bad -- can pull on his girl's heart-strings and make her cry.

Rejection Rumination

While you might want to believe that all love lasts forever, this isn't always the case. When a boy breaks things off, the feelings of rejection can quickly make the girl cry. Although rejection may make the girl feel like her now-ex doesn't value her or thinks she's not important, it more likely means that the relationship just didn't work out, according to the TeensHealth website. Crying in response to rejection is normal and can even help the girl begin the healing process.

Broken Heart

Whether a boy outright ends things with his girlfriend or he does something unseemly -- such as cheating on her -- hurting her heart emotionally is a prime reason for her to cry. Additionally, having unrequited feelings for a boy who may not truly like her or only wants a very casual type of relationship, can also cause the type of heartache that makes a girl tear up. The often powerful emotions that run deep during a relationship, even a teenage relationship, can turn from glee to tears when feelings get hurt.

Flirting and Lies

Flirting with another girl or cheating on a girlfriend with another young woman is a major cause for crying. Walking in to the school cafeteria, a party or the local hangout to find a boyfriend talking to or flirting with another girl can bring on the tears. Add a flimsy excuse, such as "We were just talking about our lab project," or "She was just asking about a class assignment," and the boyfriend's presumed lies can make his girl well up. The lack of honesty involved can make a girl feel a sense of sadness and ruin the level of trust in the relationship. Although talking to another girl on it's own isn't enough to signal a problem such as cheating, clear signs of flirting such as the boy getting physically close to the other young woman or acting like his girlfriend has just caught him doing something wrong may show that he's not trustworthy or doesn't respect his relationship.

After the Fact

When a relationship is on the verge of a breakup, or the couple has just gone through one, seeing each other after the fact can cause strife that makes the girl cry. Having to see an ex at school, on the job or at the local hangout isn't easy at any age. Seeing a boyfriend during or after the breakup can bring unhappy feelings to the surface and cause the waterworks to start flowing. While getting weepy at the sight of an ex-guy is normal for a girl, she's likely to get over it -- with the help of her family and friends -- and eventually see the boy without having to cry.