bristol palin is engaged to levi johnston againAfter a year of strife-custody battles, deadbeat allegations, and that infamous Playgirl spread, Bristol Palin, 20 (daughter of former VP candidate Sarah Palin) and Levi Johnston, 20 are engaged, again. So why the sudden change of heart, future-Mrs. Johnston? We hypothesize.

Possible Reason #1: SEX
Bristol has been adamant in interviews -- on Oprah...in a recent Us Weekly cover story...etc. -- about abstaining from the nooky until she had a ring on it. Now she's got her rock, and she and Levi want to tie the knot sooner -- within the next few months -- rather than later.

Possible Reason #2: FAME AND FORTUNE
The couple's 15 minutes in the spotlight were ticking away and they knew that telling their engagement story to Us Weekly, a magazine with a circulation of around 1.85 million, would open the floodgates to more media appearances and moolah. Seriously, though, who doesn't love a mushy engagement story?

Possible Reason #3: JEALOUSY
Imagine seeing your ex in his birthday suit plastered on the cover of Playgirl magazine. Wouldn't you be a teensy bit envious of the women across the country reading the article and gawking at the pictures? After seeing her sizzling, hot stud in the nude (in public) Miss Bristol may have had a change of heart.

Possible Reason #4:
FAMILY
Mama Palin hasn't exactly held her tongue about her dislike for Levi, calling him "Ricky Hollywood" and an attention-monger in interviews. (Which must make her "Kettle Black.") But, perhaps seeing her oldest daughter walk down the aisle into the arms of the man of her dreams will make her see him in a different light.

Possible Reason #5: LOVE
All eyes were on Bristol and Levi at the most awkward of times -- Bristol was pregnant with Tripp out of wedlock, while Bristol's mother shot to overnight fame as the Republican candidate for Vice President in one of the most popular presidential elections to date. To go through something like that at such a young age may have helped the couple form an undeniable bond. Maybe it wasn't just puppy love.