MSN.com, Match.com, HappenMagazine.com: they’re in a healthy and satisfying 3-way relationship. Meaning that you can find MSN/Match.com’s “Ask Lynn” columns –penned by BG’s alter ego — over at Happen now as well.

This week Lynn hears from Cold Front, who’s seen the same problem crop up over the years in all of her serious relationships:

I feel so sure about my feelings, but a year or more into the relationship I seem to lose interest and the desire for sex with my partner.

Is this weird or natural? Lynn examines three possibilities. Read the full letter at Happen, then come back here and tell us what you think below!