Hate to tell ya...
There's what you wish and there's how it is, no offense, but...
You will not find one man in a dozen who thinks it's okay that his wife or girlfriend gained 20lbs, let alone 70. Talk about false advertising. Sure people age, but both women and men have a responsibility to both themselves and each other to be healthy attractive mates.
Physical attractiveness is based on health (the best looking women I have ever seen were at a vegan retreat I went to in South Dakota - no makeup, hair spray, etc. and, yes, some of them even had gray hair and lines, but guess what, so healthy, they glowed and had muscle tone and were gorgeous). It stands to reason that neither males or females would willingly choose to mate with someone who is ill, i.e. overweight, poor hygiene, etc.. WE ARE DESIGNED TO FIND HEALTHY PEOPLE ATTRACTIVE NOT MAKE OURSELVES MATE WITH SOMEONE WHO IS ILL BECAUSE WE ARE "GOING STEADY" OR "WED".
Also, it is common knowledge that males are visual creatures, we love to look at women, HEALTHY women, not women who "let themselves go".
And, yes, if you do, there is a good chance we will cheat on you or find someone else. You will have plenty of warning from your own mirror...