Love = Weight gain

i have now been with my hubby 2 yrs. & 8 mos. and living together for 2 yrs. within that time span i have gained like 20 lbs!!!!! why is that we get so relaxed and just let shxt go when we are in love. i love him to death but i want my figure back =( so i am determined by my bday August 22nd to at least lose 10-15 lbs. of course he tells me i look fine but i don't feel fine. hopefully i will accomplish my goal.